Heat oil in a large nonstick skillet over medium-high heat. Add red peppers, onion and garlic. Cook 6 minutes, stirring. Add broth, 1 cup water, turmeric, black pepper, salt and red pepper flakes. Bring to a simmer and add scallops. Simmer, covered, 3 minutes. Stir in peas, sausage and clams with their liquid. Simmer, covered, 2 minutes.
Turn off heat; add couscous. Cover and let stand 5 minutes.
Fluff couscous with a fork. Serve with lemon wedges, if desired.