Heat a heavy skillet with 1/2-inch vegetable oil until hot, not smoking. Dip fish in batter to coat evenly, and lay fish strips in pan, not touching. Cook until golden, about 2 to 3 minutes. Turn and cook until golden. Drain on paper towels and season with salt, to taste. Heat a dry cast iron or heavy skillet and warm flour tortillas until heated. Assemble tortillas by layering fish, cabbage, mayonnaise, and salsa.
Stir together until incorporated.
Put ingredients in a bowl and mix.
Process ingredients together, and then simmer over medium high heat until just boiling. Serve warm. If using fresh ingredients, simmer until cooked.