Because tortillas get soggy fast, they should be consumed once prepared. But, you can prepare the beef, shrimp, coleslaw, and salad topping up to 2 days in advance. Store separately in the refrigerator, in airtight containers. Do not season or add mayonnaise to the coleslaw until ready to serve - the coleslaw may also get soggy. When ready to serve, simply reheat the beef and shrimp in an oven-safe dish in the oven or in a pan on the stove, until heated through. Add the mayonnaise and salt to the coleslaw and toast the tortillas. Then assemble the tortillas when ready to serve.