Preheat oven according to popcorn shrimp package directions.

In a bowl, combine melted butter, garlic powder, and Cajun seasoning.

Toss frozen breaded popcorn shrimp with the butter mixture to coat evenly.

Bake shrimp according to package directions until golden brown and crispy.

While shrimp is baking, prepare the sauce.

In a separate bowl, combine mayonnaise, hot pepper sauce, sweet pickle relish, and prepared mustard.

Mix well until smooth and creamy.

Warm pita pocket halves.

Spread a generous amount of sauce into each warmed pita pocket.

Fill each pita pocket with baked Cajun popcorn shrimp, shredded lettuce, and thin slices of tomato.

Serve immediately.