Baja Fish Tacos

Name: Baja Fish Tacos
Cuisine: Mexican, Latin American, TexMex, American
Ingredients: 1.5 lbs mahi mahi; 2 cups all purpose flour; 2 teaspoons salt; 1 teaspoon pepper; 1 teaspoon baking powder; 1 teaspoon baking soda; 1 teaspoon paprika; 1 tablespoon mustard; 12oz beer of choice (light beer recommended); 4 cups vegetable oil; 1/2 piece purple cabbage; 1/3 cup cilantro; 2 fresh jalapeño peppers; 2 limes; 1 tablespoon apple cider vinegar or red wine vinegar; 2 tablespoons olive oil 1 teaspoon dried oregano; 1 tomato; 1/4 piece white onion; 1 cup sour cream; Corn tortillas to serve; 1 tablespoon of mayonnaise