The day before prepare Yum Yum sauce buy putting ¼ bottle in the food processor and the 3 Serrano peppers, blend until Serrano's are mixed in well. Add the rest of the bottle to the mixture and give this a good mix, then put in the refrigerator overnight. (This sauce sitting overnight allows the 2 ingredients to marry well.
Make the breading for the shrimp, bread them, and deep fry until done. Allow to drain on paper towel.
Shred the purple cabbage (do not chop, you are looking for texture as well as the taste)
Warm your flour shells.
Place the purple cabbage on the shell 1st then spoon yum yum sauce over the cabbage (as much as you desire, it is all preference). Put your shrimp about 6 or 7 pieces per taco on top of the sauce and sprinkle sharp cheddar cheese on top of the shrimp. Use a kitchen blow torch to melt the cheese onto the shrimp and enjoy. If you do not have a blow torch you can put it under the broiler long enough to melt the cheese. I find the kitchen blow torch faster and easier.