Place oven racks in center and upper third positions of oven. Preheat oven to 400°F. Toss together shrimp, bell peppers, poblano, onion, oil, chili powder, cumin, 5/8 teaspoon salt, and coriander on a baking sheet lined with aluminum foil. Place on middle rack of oven; roast until shrimp are cooked through, 9 to 10 minutes. Transfer shrimp to a plate, reserving remaining vegetable mixture on baking sheet. Cover shrimp with foil to keep warm.
Turn broiler to high. Broil vegetables on upper oven rack until slightly charred, 3 to 4 minutes, and set aside. Stir together sour cream, chopped cilantro, jalapeño, lime zest and juice, garlic, and remaining 1/8 teaspoon salt in a bowl.
Spoon shrimp and vegetables evenly onto warm tortillas; top with sour cream mixture. Sprinkle with cilantro leaves; serve with lime wedges.