Vegan Roasted Cauliflower Soup with Potatoes, Lemon & Rosemary

4.89 from 18 votes

Vegan roasted cauliflower soup with potatoes, lemon, and rosemary is simple to make, super satisfying, and just so delicious.

An overhead shot of a bowl of vegan roasted cauliflower soup, garnished with croutons and chopped parsley. The soup is beige. The bowl is on a beige napkin, which is on top of a wooden cutting board.
An overhead, off-entered shot of a head of cauliflower in plastic wrap. The label says “Chou Fleur” in blue.

This vegan roasted cauliflower soup recipe is easy in many ways. There are 5 seasonal and accessible main ingredients. It’s just a roast and blend kind of affair, so there’s minimal hands-on time. A bowl is so warm and filling on its own, while the flavour and satisfaction is easy to appreciate as well.

There are obvious creamy and nutty qualities, but just the right high note of acidity from a squeeze of lemon waves hello when needed. Rosemary is woodsy and warm. Potatoes combine with the cauliflower to make a seriously creamy purée. This is a recipe I count on in the closing phase of Winter. There is much to anticipate—the seedlings and building projects of warmer days, but for now there are hardy vegetables and hot ovens to stay loyal to.

In the past couple weeks I’ve made not one, but two things that were total failures. The first was a batch of gluten free and vegan cinnamon buns that just flopped in every way. The second mishap was a flax granola that was, as I suspected it would be, much too flax-y for my liking. One day they will come to me (but not actually on that flax granola—wiping my hands of that). Tenured chefs get it wrong sometimes and the thought of this provides comfort, a laugh and the motivation to move on.

So I moved on to something I knew front to back and all through the dreamy middle. I used to cook at a little café and when I made it up, this roasted cauliflower soup was always received with a certain surprised approval. The rosemary fragrance and deep-warming nature of it brought people around I think. More simple blended soup goodness in the form of this kabocha squash one here, coconut green soup here, or this fennel walnut soup with turmeric here.

Hope you’re all having some cozy and easy days by the oven or wherever you like to be. I had a brief glimpse of sunbeams and chirping birds on an outing today, so I know that the world is at work on something wonderful for us all over again in the coming months. Be warm in the meantime!

2 photos: one is a sprig of rosemary on top of a wooden cutting board. The other is an overhead shot of a roasting tray with browned onions, cauliflower, and potatoes with a squeezed lemon half.
An overhead shot of a bowl of vegan roasted cauliflower soup, garnished with croutons and chopped parsley. The soup is beige. The bowl is on a beige napkin, which is on top of a wooden cutting board.

Vegan Roasted Cauliflower Soup with Potatoes, Rosemary & Lemon

Vegan roasted cauliflower soup with potatoes, lemon, and rosemaryis simple to make, super satisfying, and just so delicious.
4.89 from 18 votes
A slight 3/4 angle shot of vegan roasted cauliflower soup. The soup is beige and topped with croutons, chopped parsley, and balsamic reduction. It is in a white bowl on a beige napkin, on top of a black background.
Prep Time: 15 mins
Cook Time: 1 hr
Total Time: 1 hr 15 mins
Servings 4 -6



  • 1 large head of cauliflower
  • 1 lb yukon gold potatoes, scrubbed
  • 2 medium yellow onions, papery skin removed
  • 1-2 tablespoons fresh rosemary leaves
  • 2 tablespoons olive oil
  • sea salt and ground black pepper, to taste
  • 1 tablespoon fresh lemon juice
  • 5-6 cups vegetable stock

To Serve (optional)

  • more olive oil
  • croutons
  • toasted and chopped nuts
  • chopped leafy herbs
  • balsamic reduction
  • squeezes of lemon
  • more ground black pepper



  • If you aren’t using homemade stock, most definitely use a no-salt-added variety. I advise on liberally salting the vegetables pre-roasting, so being in control of this factor throughout is ideal.
  • If you’re avoiding extra carbohydrates, you can simply leave the potatoes out of the recipe and double up the cauliflower. 


  • Preheat the oven to 400°F.
  • Remove the core from the cauliflower and chop it into rough florets. Place the florets into a 9 x 13 glass baking dish.
  • Chop the potatoes into pieces about half the size of the cauliflower florets and toss them into the baking dish as well.
  • Chop the onions into rough 1-2 inch pieces and toss them into the dish. It doesn't matter if the onion layers stick to each other.
  • Sprinkle the rosemary leaves over the vegetables in the dish. Liberally salt the vegetables and season with pepper to taste. Add the oil and toss the vegetables until evenly coated with the oil, rosemary, and seasoning.
  • Roast vegetables for about an hour, flipping and tossing them here and there with a spatula/spoon to promote even browning. When done, remove from the oven and pour the lemon juice over the hot vegetables (I just drop the lemon half into the warm pan when I'm done so that it can release some oil too). Using your spatula, toss the vegetables with the lemon juice, scraping the browned bits off the bottom.
  • Once the vegetables are cool enough for you to handle, start blending them in batches with the vegetable stock. Purée until smooth and pour into a big soup pot. Continue blending in batches until you've used up everything. Heat the larg pot full of puréed soup over medium heat until it comes to a boil. Add more stock or water to thin the soup out if necessary and adjust seasoning to taste. Serve hot with optional garnishes.
20/02/2013 (Last Updated: 20/02/2013)
Posted in: autumn, creamy, earthy, gluten free, grain-free, main course, nut free, quick, refined sugar-free, roasted, salty, soup, sour, spring, summer, vegan, winter
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