1 cup all-purpose flour
2 tablespoons cornstarch
1 teaspoon baking powder
1/2 teaspoon salt
1 egg
1 cup beer

1/2 cup plain yogurt
1/2 cup mayonnaise
1 lime, juiced
1 jalapeno pepper, minced
1 teaspoon minced capers
1/2 teaspoon dried oregano
1/2 teaspoon ground cumin
1/2 teaspoon dried dill weed
1 teaspoon ground cayenne pepper

1 quart oil for frying
1 pound cod fillets, cut into 2 to 3 ounce portions
1 (12 ounce) package corn tortillas
1/2 medium head cabbage, finely shredded