Mix together the mayonnaise, lime juice, chili powder, garlic, and some salt and pepper; taste, adjust the seasoning, and set aside.
Put the oil in a large skillet over medium-high heat. Sprinkle the fish with salt and pepper, then dredge both sides of the fillets in the flour; dip in the egg, and coat in the bread crumbs. When the oil is hot, add the fillets and cook until golden brown on both sides, about 8 minutes total.
To assemble the sandwiches, smear the rolls with the chili lime mayo, add the fillets (cut in half to fit on the bun as necessary), and top with tomato slices, cabbage, and cilantro if you’re using it.
This sandwiches must be Served immediately.
¼ cup mayonnaise
2 tablespoons freshly squeezed lime juice
1 tablespoon chili powder
1 teaspoon minced garlic
Salt and freshly ground black pepper
¼ cup neutral oil, like grape seed or corn, plus more as needed
Four 4 ounce fillets of firm white fish, like cod, halibut, or