1. Preheat oven to 450 degrees F. In a shallow baking pan combine 1/2 red sweet pepper, thinly sliced; 1/2 yellow sweet pepper, thinly sliced; and 1 thinly sliced red onion. Sprinkle with 1 Tbs. olive oil, 2 tsp. chili powder, 1/4 tsp. salt, and pepper to taste. Toss to coat, then spread in a single layer. In a separate shallow baking pan, combine 1 1/2 lb. peeled and deveined shrimp, 1 Tbs. olive oil, 1 tsp. chili powder, 1/4 tsp. salt, and pepper to taste. Toss to coat, then spread in a single layer. Roast the vegetables and shrimp, stirring once halfway through, until the vegetables are lightly browned and the shrimp are cooked through, about 8 minutes. In a small bowl stir together 1/2 cup plain low-fat Greek yogurt, 1/4 tsp. lime zest, 1/2 tsp. lime juice, 1 small grated garlic clove and 2 tsp. chopped fresh cilantro. Serve the vegetables and shrimp in warm tortillas with the yogurt sauce and cilantro sprigs. Garnish with lime wedges.