- Clean and devein the shrimp. 
- Heat oil in a pan over medium heat. Add onion and cook until softened. 
- Add the shrimp, Old Bay seasoning, and onion powder to the pan. Cook for 5–7 minutes or until pink in color. 
- In another pan over medium heat, heat the tortillas until lightly golden. 
- Assemble tacos by adding shrimp mix, cheese, sour cream, salsa, cilantro, and green onion into each taco. Serve with diced tomatoes and wedges of lime. 
- Slice avocado and add to tacos as desired.