To make the pickled onions combine the onions and jalapenos in a medium bowl. Set aside.

Place the vinegar ,lime juice, sugar, and pepper in a small saucepan and bring to a boil. Remove from heat and pour over top of onion mixture. Allow to sit for 30 minutes. Refrigerate until ready to use.

To make the cabbage, take 1/4 c. pickling liquid from the onions and toss in a bowl with all the ingredients for the pickled cabbage. Toss to coat. Refrigerate until ready to use.

To make the white sauce simple whisk all ingredients together in a bowl and refrigerate until ready to use.

Preheat the oven to 225 degrees. Set a wire rack inside a rimmed baking sheet. Set aside.

Sprinkle the fish with salt and pepper and set aside.

In a medium bowl combine the flour, cornstarch, and baking powder. Add beer and whisk until smooth.

Add the fish pieces to the bowl and toss until the fish is coated.

Add the vegetable oil to a deep skillet. Heat over medium high heat to 350 degrees.

Remove the fish from the batter, 4-5 pieces at a time, allowing excess batter to drip off. Add the fish to the hot oil and fry for 2-3 minutes per side or until golden brown.

Remove from the pan and place on wire rack on the baking sheet. Place in the oven to keep warm.

Repeat with remaining fish.

To serve the tacos place a few pieces of fish on a tortilla. Top with pickled onions and cabbage. Drizzle with white sauce and sprinkle with cilantro.