At Willow restaurant in Arlington, Va., chef Tracy O'Grady tops this soup with croutons and with Gruyere and provolone cheeses, then runs it under the broiler. She says: "This is a little more work and makes a heartier soup that is perfect as a main meal with a salad. So you can have a lighter or heartier version."
4 1/2 tablespoons extra-virgin olive oil
1/2 cup carrot, cut into small dice
1/2 cup onion, cut into small dice
1/2 cup celery, cut into small dice
1/2 cup fennel, cut into small dice
1 small leek, white and light-green parts cut in half lengthwise, then each half cut crosswise into thin slices to yield 1/2 cup and soaked briefly in water to remove grit
5 cloves garlic, thinly sliced
Crushed red pepper flakes
1/2 cup diced fresh or good-quality canned tomatoes
1/2 cup dry sherry (optional)
1 tablespoon sherry vinegar
12 stems thyme, tied with kitchen twine into a bouquet
8 cups vegetable broth or water
2 cups mixed summer beans or peas of your choice, each variety cooked separately until just tender (possibilities include shell beans, fresh lima beans, fava beans, green or yellow beans, peas, snap peas)
2 tablespoons chopped basil leaves
Cracked black pepper
9 tablespoons prepared pesto
Heat 2 1/2 tablespoons of the oil in a 4-quart nonreactive soup pot over medium heat. Add the carrots, onions, celery, fennel, leek and garlic; cook gently, stirring frequently, for 6 to 8 minutes, until tender and translucent. Add the crushed red pepper flakes and tomatoes and cook for 10 minutes. Add the sherry, if using, and the sherry vinegar, scraping the bottom of the pot to dislodge any browned bits. Cook until the liquid in the pot has reduced by half. Add the thyme bouquet and the broth or water and bring to a boil over medium-high heat, then reduce the heat to medium or medium-low (as needed) and cook for 20 minutes, adjusting the heat so that the liquid is barely bubbling at the edges.
Just before serving, add the cooked beans and peas; bring the liquid to a boil over medium-high heat. Remove from the heat; discard the thyme bouquet and stir in the basil leaves.
Season with salt and pepper to taste. Ladle into individual bowls; top each serving with 1 tablespoon of pesto and drizzle equally with the remaining 2 tablespoons of oil.
Per 1-cup serving: 220 calories, 5 g protein, 18 g carbohydrates, 14 g fat, 2 g saturated fat, 0 mg cholesterol, 390 mg sodium, 3 g dietary fiber, 5 g sugar