For the cilantro-lime sauce

1. Blend sauce. Put all ingredients for the sauce in a blender or food processor and blend until smooth. Season with salt to taste. Set aside.

For the fish

1. Make batter. In a medium bowl, whisk together flour, cornstarch, baking powder, a pinch of salt and pepper. Add 3/4 cup beer and whisk to combine. Batter should be slightly liquid but still thick enough to coat the fish. Add more beer to thin batter if necessary.
2. Fry fish. In a deep, heavy fry pan or sauté pan over medium-high heat, pour in oil to a depth of 1 inch. Heat the oil to 375 degrees. While the oil is heating, pat the fish dry with paper towels and season with salt and pepper. Cut the fish into pieces about 3 inches long by 1/2 inch square. Working in batches, dip the fish pieces into the batter, and then carefully slide the fish into the hot oil. Fry the fish, turning the pieces regularly, until they are golden brown and crispy, about 4-7 minutes. Drain the fried fish on paper towels and keep warm in a low oven while you fry the rest of the fish.

For serving

1. Make slaw. Toss the shredded cabbage with 2-3 tablespoons of the cilantro-lime sauce.
2. Serve. Place desired amount of cabbage slaw on a warm tortilla, top with fish and a spoonful of sauce and pico de gallo. Add a squeeze of fresh lime juice, if desired, and serve.