Defrost the Shrimp - If using frozen shrimp, place them in a colander and run cold water until no longer icy, about 3 minutes. Alternatively, set in a bowl and fill with room temperature water until defrosted. Thoroughly drain and pat dry using paper towels.
Cajun Seasoning - In a medium bowl, combine shrimp, 1 tablespoon olive oil, paprika, salt, garlic powder, onion powder, black pepper, oregano, cayenne pepper, and red pepper flakes.
Saute the Vegetables - Heat a 12-inch skillet or cast iron pan over medium heat. Add 1 tablespoon olive oil. Once hot, add the garlic and saute until fragrant, 30 seconds.Add the onion, saute for 90 seconds. Add the red and green bell peppers, saute for 1 minute. Transfer vegetables to a clean bowl.
Cook the Shrimp - Melt the butter in the pan. Add the shrimp in a single layer. Cook without moving until they turn pinkish on the bottom and start to curl, about 2 minutes. Flip and cook until curled into a loose “C” shape, about 1 minute.
Combine Ingredients - Add the sauteed vegetables and stir to combine, 1 minute, then turn off the heat. Transfer to a serving platter. Garnish with parsley and serve with lemon wedges.
Notes
Make it Spicier: Use ¼ teaspoon cayenne pepper or ¼ teaspoon red pepper flakes.