Combine sour cream, 1 1/4 teaspoons hot pepper sauce, and 1/2 teaspoon chili powder.
Combine remaining 3/4 teaspoon chili powder, cumin, garlic powder, paprika, and salt in a large bowl. Add shrimp; toss to coat. Let stand 10 minutes.
Heat oil in a large nonstick skillet over medium-high heat. Add garlic; sauté 30 seconds. Add shrimp mixture; sauté 3 minutes or until done. Stir in remaining 2 teaspoons hot pepper sauce and juice. Remove from heat.
Heat tortillas according to package directions. Arrange about 2 ounces shrimp, 1/4 cup lettuce, and 1 tablespoon onion down center of each tortilla. Serve with sour cream mixture and salsa verde.