In a small bowl, combine all the fish taco sauce ingredients and mix with a spoon until fully combined. Set aside.
Next, make the fish fry batter. In a medium bowl, combine 1 cup flour, ¼ cup cornstarch, ½ tbsp garlic and onion powder, 1 tsp cumin and oregano, ½ tsp smoked paprika, ½ tsp salt, ¼ tsp cayenne pepper, ½ cup beer, and ¾ cup water. Mix to combine, until the batter is smooth.
Add the vegetable oil to a large skillet and heat over high heat until the oil reaches 350 degrees Fahrenheit.
When the oil is hot, dip the individual fish pieces into the fish fry batter, dropping the battered fish into the oil. Make sure to fry in batches as you don’t want to overcrowd the skillet.
Fry for 2-3 minutes on each side until the fish is golden brown. Then remove the fish to a paper towel lined plate and repeat until all of the fish is cooked.
When all of the fish is cooked, heat the corn tortillas on a dry, hot skillet for 10-20 seconds on each side until char marks form.
Take the heated tortilla and lay down a layer of the coleslaw mix. Add a piece of fish into the taco as well as some avocado cubes, cotija cheese, a drizzle of fish taco sauce, and a squeeze of lime (if desired).
Serve and enjoy!