

For the Broth: Combine the onions, carrot, celery, leek, fennel, garlic, oil and salt in a large Dutch oven. Cover and cook over low heat, stirring often, until the vegetables have softened, 8 to 10 minutes. Stir in the broth, peppercorns, thyme and parsley. Bring to a boil over medium-high heat; reduce the heat to medium-low and simmer until the broth is flavorful, about 15 minutes. Strain the broth through a fine-mesh strainer; discard the solids. (The broth can be refrigerated for up to 3 days or frozen in an airtight container for up to 2 months.)
For the Soup: Bring the broth to a simmer in a large saucepan over medium heat. Add the potatoes and leeks and simmer for about 5 minutes. Add the asparagus and cook until all the vegetables are just tender, about 5 minutes. Off the heat, stir in the spinach, peas, and tarragon, cover, and let sit until heated through, about 4 minutes. Season with salt and pepper to taste. Serve immediately.
Per 1 1/2-cup serving: Cal 120; Fat 1.5 g; Sat fat 0 g; Chol 0 mg; Carb 22 g; Protein 6 g; Fiber 5 g; Sodium 930 mg
This recipe was featured as Cook's Illustrated's "The Best Light Recipe"