This soup might seem plain with only three ingredients, but Paul Bertolli knows exactly how to make a vegetable become the best it can be. This recipe is from his book Cooking by Hand, and makes for a soup that's delicate, sweet, and a pure expression of cauliflower. 

Note: This formula works with cauliflower or romanesco. The natural pectin in these two vegetables makes for a smooth, thick, puree. It won’t work with broccoli, squash, etc.

3 tablespoons olive oil

1 medium onion, sliced thin

1 head very fresh cauliflower (about 1-1/2 pounds), broken into florets

Salt, to taste

5 1/2 cups water, divided

Extra virgin olive oil, to taste

Freshly ground black pepper, to taste

Warm the olive oil in a heavy-bottomed pan. Sweat the onion in the olive oil over low heat without letting it brown for 15 minutes.

Add the cauliflower, salt to taste, and 1/2 cup water. Raise the heat slightly, cover the pot tightly and steam the cauliflower for 10-15 minutes. Then add another 4 1/2 cups hot water, bring to a low simmer and cook an additional 20 minutes uncovered.

Working in batches, purée the soup in a blender to a very smooth, creamy consistency. Let the soup stand for 20 minutes. In this time it will thicken slightly.

If desired, thin the puree with 1/2 cup hot water. Reheat the soup. Serve hot, drizzled with a thin stream of extra-virgin olive oil and freshly ground black pepper.