Prepare spicy sauce by shaking together sour cream and sriracha in a squeeze bottle. (Refrigerate leftovers)
Place raw frozen shrimp in colander and rinse with room temperature water to remove frost. Pat dry with towel so that shrimps can get a nice crispy, golden brown sear and don't steam in the pan and become rubbery.
Melt 1 tbsp butter over medium heat in a skillet and add shrimp. Stir frequently and cook just until shrimps have all turns pink. Remove from heat and set aside, keeping warm.
Melt remaining 1 tbsp butter in skillet. Add pineapples and cook until edges are golden brown. Remove from skillet and let cool.
Briefly place soft taco shells on skillet to soften and warm both sides. Arrange two of three shells on a plate. Fill with a layer of cabbage. Top with shrimp.
Prepare salsa by tossing all ingredients together. Add salsa on top of shrimp then finally top with spicy sauce.