What you’ll need
For a rich and flavorful seafood stock, sauté about 4 cups of crab and shrimp shells until fragrant. Then, stir in the green tops from 1 leek or 1 small chopped onion along with 1 tablespoon tomato paste, 1 bay leaf, 1 teaspoon whole peppercorns, 6 thyme sprigs, and 6 cups of water. Bring to a boil. Simmer, uncovered, over low heat until richly flavored, about 30 minutes. Strain and use right away or freeze in an airtight container for up to 1 month.