​Peak season for cauliflower is from September through November and n our CSA box for week 23 and 24 we received a head of white cauliflower and the following week, purple. The white cauliflower was transformed into a delicious and velvety cream of cauliflower soup. I was unsure what to do with a purple head, until I read the Cook’s notes for Melissa Clark’s recipe for Lemony Carrot and Cauliflower Soup. The commenter suggested using purple cauliflower. 
​For the soup you’ll need coriander seeds, extra-virgin olive oil, white onion, fresh garlic, approximately one pound of carrots, kosher salt, a head of cauliflower, lemon zest and juice and for serving smoky chile powder, coarse sea salt and cilantro leaves.
 
Instead of using tap water for the soup, I used homemade chicken stock. Instead of coriander seeds, ground coriander. I added the coriander while sautéing the onions to bloom the flavor. For serving, I skipped the suggested condiments.
 
The soup was very easy to prepare. If prepared with water, it can be vegan, depending on your miso ingredients. After pureeing the soup, I added the lemon juice and zest. What was fascinating was the chemical reaction between the purple cauliflower (it contains a natural pH indicator) and the lemon juice (an acid). When added to the soup, the area turned bright pink! After stirring the mixture into the soup, the rest of the soup turned a pretty shade of pink.
 
This was a hit with my husband! The lemon juice really added another layer of flavor. The combination of carrots and cauliflower with a hint of onion made for a tasty soup. You must give this one a try!
Lemony Carrot and Cauliflower Soup
“When Fuzzy Slippers Aren’t Enough”
By Melissa Clark, March 4, 2013
The New York Times/What’s for Dinner? column
 
Yield: 4 Servings
Time: 40 Minutes
 
INGREDIENTS
1 tablespoon coriander seeds
2 tablespoons extra-virgin olive oil, more for serving
1 large white onion, peeled and diced (2 cups)
2 large garlic cloves, finely chopped
5 medium carrots (1 pound), peeled and cut into 1/2-inch pieces (2 cups)
1 ½ teaspoons kosher salt, more as needed
3 tablespoons white miso
1 small (or half of a large) head cauliflower, trimmed and cut into florets*
½ teaspoon lemon zest
2 tablespoons lemon juice, more to taste
Smoky chile powder, for serving
Coarse sea salt, for serving
Cilantro leaves, for serving
 
PREPARATION
  1. In a large, dry pot over medium heat, toast coriander seeds until fragrant and dark golden-brown, 2 to 3 minutes. Transfer to a mortar and pestle and coarsely crush.
  2. Return the pot to medium heat. Add the oil and heat until warm. Stir in onion; cook, stirring occasionally, until soft and lightly colored, 7 to 10 minutes. Stir in garlic and cook 1 minute.
  3. Add carrots, crushed coriander, salt and 6 cups water to the pot. Stir in the miso until it dissolves. Bring mixture to a simmer and cook, uncovered, 5 minutes. Stir in cauliflower and cook, covered, over medium-low heat until the vegetables are very tender, about 10 minutes.
  4. Remove the soup from the heat. Using an immersion blender, purée the soup until smooth. (Alternatively, you can let soup cool slightly then purée it in batches in a food processor or blender.) If necessary, return the puréed soup to the heat to warm through. Stir in the lemon zest and juice just before serving. Drizzle with oil and sprinkle with chile, sea salt and cilantro leaves.
 
*I used a head of purple cauliflower that I received in my CSA box. After reading some of the comments, I used chicken stock that I had made and added not only the lemon juice, but zest. The acid from the lemon transformed my light purple soup into a pretty shade of rose.