Cauliflower Potato Leek Soup
This cauliflower potato leek soup is hearty, velvety smooth, and flavorful! Serve alongside these insanely good air fryer parsnip chips to enjoy a bounty of delicious spring veggies!
I didn’t even know I liked leeks until I made this cauliflower potato leek soup! As spring is drawing to a close, I wanted to try out some new recipes using some spring veggies like parsnips, leeks, and fennel. The parsnip chips I recently shared are still my favorite recipe from this season, but this soup is a close second!
The taste of this rich, comforting soup is reminiscent of a loaded baked potato, but with the addition of smokey roasted veggies!
🥄 Why This Recipe Works
- This potato leek and cauliflower soup is gluten-free! The roasted cauliflower not only adds flavor to the soup but also helps to thicken it without the use of flour.
- You can substitute the chicken broth/bacon with plant-based alternatives to make this recipe vegetarian-friendly.
- For a dairy-free version, you just need to make a few simple swaps, opting for a heavy cream alternative and a plant-based cheese.
🛒 What You Need To Make Cauliflower Potato Leek Soup
📝 Recipe Modifications And Substitutions
- Leeks: You’ll need 2-4 leeks. We won’t use the dark green parts, so when choosing your leeks, look for ones that have long white/light green bulbs.
- Potatoes: I suggest using russet potatoes or Yukon gold potatoes for a smooth, creamy texture.
- Cauliflower: You can use a fresh head of pre-sliced cauliflower florets.
- Onion: I recommend using yellow or white onion.
- Chicken broth: Or vegetable broth.
- Jalapeno: You can also use serrano, or omit it entirely.
- Heavy cream: Or half & half.
- Chives: You can also use green onion/scallions.
- Cheese: I like to use shallot & chive Boursin, but you can also use the garlic & herb flavor, freshly grated cheddar cheese, or your preferred cheese.
- Herbs & spices: Thyme, bay leaf, fresh garlic, white or black pepper, salt, and smoked paprika all work wonderfully, but you can also work in parsley, shallot, sage, rosemary, cayenne, red pepper flakes, nutmeg, etc.
- Optional ingredients: Fennel, when roasted, adds a buttery, slightly sweet flavor when roasted, similar to roasted cabbage or roasted onion. You can use 1-2 large bulbs. Bacon is a great topping for adding a little texture and salty flavor before serving.
*See above image or recipe card for full list of ingredients
🥣 What Equipment Do I Need?
You will need a large saucepan, pot, or Dutch oven, an immersion blender (or stand blender), a cookie sheet, parchment paper, and a fine-mesh strainer. You’ll also need a small saucepan for infusing the cream.
🥘 How To Make This Recipe
Step 1: Start by roughly chopping a yellow onion and 1-2 jalapenos, then add them to a pot along with black peppercorns and 2 Tbsp olive oil. Allow the ingredients to sweat over medium-low heat for about 5 minutes or until onions start to become slightly translucent. Add in heavy cream and bring to a light simmer for about a minute. Cover and turn off the heat, then set aside for at least 30 minutes.
Pro Tip: It’s okay to roughly chop the onion & jalapenos because we’ll be straining & discarding them after allowing the cream to infuse with their flavor.
Step 2: Meanwhile, chop the bottom off of the fennel bulb and discard, along with the green fronds and any bruised pieces. Slice the bulb in half, then into thin wedges.
Step 3: Toss fennel wedges along with sliced cauliflower florets in a bowl with 4 Tbsp olive oil, smoked paprika, salt, and white or black pepper. Assemble on a baking sheet lined with parchment paper and roast in the oven at 400° F for 10-20 minutes. Flip the pieces, then roast for another 10-20 minutes.
Step 4: Slice off the bottom of the leeks and the thick green leaves and discard. Cut the bulb in half and rinse thoroughly to remove any dirt that might be trapped between the layers. Place cut-side-down on a cutting board and thinly chop.
Step 5: Add to a large pot with 2 Tbsp olive oil and saute for 5-10 minutes or until leeks lose about half their volume. Add in minced garlic cloves and toast for 1-2 minutes or until fragrant.
Step 6: Add roasted cauliflower and fennel to the pot, along with peeled & chopped potatoes, chicken broth, dried thyme, and 1-2 bay leaves.
Step 7: Bring to a boil, then cover and simmer over medium-low heat for 20 minutes or until potatoes are fork-tender. Remove bay leaves then use an immersion blender to blend until your desired texture is reached.
Pro Tip: I like mine smooth, but if you want to maintain some of the texture you can blend half the soup and maintain the chunks in the other half.
Step 8: Use a fine-mesh strainer to strain the chunks from the cream. Press with a wooden spoon or ladle to squeeze out as much of the cream as possible. Mix the infused cream into the soup along with Boursin cheese and stir over low heat until consistent. Discard the onion mixture.
Step 9 (optional): Fry a few slices of bacon and crumble over plated soup to garnish, along with chives and/or fennel fronds.
👩🏻🌾 Zero-Waste Tips
If you’re a multi-use/zero-waste queen like me, you may want to find alternate uses for the green leaves of the leeks, rather than discarding them. Here are some ideas:
- Blanche the leek tops in boiling water for 2 minutes, then drain and pickle them using the brine from my quickles recipe.
- Chop & saute leek leaves in a little oil to soften them, then add them to this jalapeno pesto.
- Freeze them in a bag along with other vegetable scraps and use them to make your own vegetable or chicken broth.
- Saute them and add them to this delicious asparagus pea and leek risotto.
- Chop them into pieces about 1-2 inches wide and dehydrate them. You can enjoy them as chips or grind them into a powder you can add to various dishes for a boost of flavor.
- Thinly slice them and add them to this spicy vegan japchae or other stir-fries.
You can also reuse the onion mixture! Just remove the peppercorns and then you can use what’s left to make other dishes.
- Use it to make queso blanco or other creamy dips.
- Blend & freeze it and add it to a soup or pasta sauce at a later time.
- Use it to make a soubise sauce with a kick!
🍲 More Delicious Soups To Try
Try some of these other hearty & comforting soups!
- Roasted cauliflower and pumpkin soup
- 10 vegetable soup
- Gluten-free cream of mushroom soup
- Vegan tom kha soup
🤷🏻♀️ Recipe FAQs
Leeks come in all shapes and sizes, but for most recipes, you want to choose ones that have long white (or light green) bulbs/”stems”. The flat, dark green leaves are tough and fibrous and usually get discarded. Look for leeks that are firm, healthy-looking, and aren’t turning brown or slimy.
You may need to add additional seasoning if your soup tastes bland. Perhaps your spices are losing their potency due to age or maybe you thinned the soup with water and this threw off the balance of the flavors. Always taste as you go and adjust as needed!
👩🏻🍳 Pro Tips
- I used 1 large fennel bulb and the flavor was very mild. You can use 2 bulbs if you want it to be more of a prominent flavor.
- If you want to add more texture to your leek potato & cauliflower soup you can reserve some of the sauteed leeks or separately boil & dice a potato and mix it into the soup at the end.
- Top with thinly sliced fresh jalapeno if you like a little heat!
- If the soup is too thick, you can add 1-2 cups of water or broth to thin it out.
- You can never go wrong with some fried baguette or toasted sourdough bread on the side (or your gluten-free bread of choice).
- Store leftovers in an airtight container for up to 5 days in the fridge, or 3 months in the freezer.
Love this cauliflower and pumpkin soup recipe? Please leave a 5-star 🌟🌟🌟🌟🌟 rating in the recipe card below & a review in the comments section further down the page.
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Cauliflower Potato Leek Soup
Ingredients
- 1 small yellow onion
- 1-2 jalapenos
- 2 tsp black peppercorns
- ½ cup olive oil (divided)
- 2 cups heavy cream
- 1 large fennel bulb
- 2 cups cauliflower florets
- 1/8 tsp smoked paprika
- ½ tsp sea salt
- ¼ tsp white pepper
- 3 large leeks
- 2 garlic cloves
- 2 medium russet potatoes
- 4 cups chicken broth
- ¼ tsp dried thyme
- 1-2 bay leaves
- 2.5 oz shallot & chive Boursin cheese
- 4 slices bacon
- 1 Tbsp fresh chives
Instructions
- Start by roughly chopping a yellow onion and 1-2 jalapenos, then add them to a pot along with black peppercorns and 2 Tbsp olive oil. Allow the ingredients to sweat over medium-low heat for about 5 minutes or until onions start to become slightly translucent. Add in heavy cream and bring to a light simmer for about a minute. Cover and turn off the heat, then set aside for at least 30 minutes.
- Meanwhile, chop the bottom off of the fennel bulb and discard along with the green fronds and any bruised pieces. Slice the bulb in half, then into thin wedges.
- Toss fennel wedges along with sliced cauliflower florets in a bowl with 4 Tbsp olive oil, smoked paprika, salt, and white or black pepper. Assemble on a baking sheet lined with parchment paper and roast in the oven at 400° F for 10-20 minutes. Flip the pieces, then roast for another 10-20 minutes.
- Slice off the bottom of the leeks and the thick green leaves and discard. Cut the bulb in half and rinse thoroughly to remove any dirt that might be trapped between the layers. Place cut-side-down on a cutting board and thinly chop.
- Add to a large pot with 2 Tbsp olive oil and saute for 5-10 minutes or until leeks lose about half their volume. Add in minced garlic cloves and toast for 1-2 minutes or until fragrant.
- Add roasted cauliflower and fennel to the pot, along with peeled & chopped potatoes, chicken broth, dried thyme, and 1-2 bay leaves.
- Bring to a boil, then cover and simmer over medium-low heat for 20 minutes or until potatoes are fork-tender. Remove bay leaves then use an immersion blender to blend until your desired texture is reached.
- Use a fine-mesh strainer to strain the chunks from the cream. Press with a wooden spoon or ladle to squeeze out as much of the cream as possible. Mix the infused cream into the soup along with Boursin cheese and stir over low heat until consistent. Discard the onion mixture.
- Fry a few slices of bacon and crumble over plated soup to garnish, along with chives and/or fennel fronds.
Notes
- It’s okay to roughly chop the onion & jalapenos because we’ll be straining & discarding them after allowing the cream to infuse with their flavor.
- I like mine smooth, but if you want to maintain some of the texture you can blend half the soup and maintain the chunks in the other half.
- I used 1 large fennel bulb and the flavor was very mild. You can use 2 bulbs if you want it to be more of a prominent flavor.
- If you want to add more texture to your leek potato & cauliflower soup you can reserve some of the sauteed leeks or separately boil & dice a potato and mix it into the soup at the end.
- Top with thinly sliced fresh jalapeno if you like a little heat!
- If the soup is too thick, you can add 1-2 cups of water or broth to thin it out.
- You can never go wrong with some fried baguette or toasted sourdough bread on the side (or your gluten-free bread of choice).
- Store leftovers in an airtight container for up to 5 days in the fridge, or 3 months in the freezer.
