If you're making the Curtido, start by slicing up the cabbage (approx. 1/3 head), 1/4 onion, and 1/4 jalapeno. Add them to a mixing bowl along with the remaining ingredients: 1/2 cup vinegar, 3/4 cup water, 1/2 teaspoon Mexican oregano (optional), 1 teaspoon of salt, and some freshly cracked black pepper. Combine well and add everything to a Mason jar. Give it a shake and let it rest in the fridge until you need it.
For the Chipotle Crema, add the following ingredients to a blender or food processor and combine well: 1 cup mayonnaise, 2 chipotles in adobo, 2 garlic cloves, pinch of salt, and a squeeze of lime. You might need to add a splash of water to get it to combine. If you want more heat you can add more chipotles or some of the adobo sauce. Keep in mind that you can substitute some of the mayonnaise for plain Greek yogurt.
Pat dry and season the fish on both sides with salt. Cut into strips that are approximately 1" x 3".
To make the beer batter, add the following ingredients to a mixing bowl: 1 cup flour, 1 teaspoon baking powder, 1 teaspoon salt, freshly cracked black pepper, and 1 teaspoon chili powder (optional). Combine well and then add 1 cup of beer. Whisk together until you have batter that is the consistency of thick paint, adding more beer if necessary (I added an additional 1/4 cup of beer to this batch.)
Preheat 3-4 cups of oil in a saucepan until it reaches 350-360F (I used canola oil). One at a time, dip the fish sticks into the batter and drop them gently into the oil. Let them cook for 3-4 minutes or until the exterior is turning a darker brown. I used a narrow pan and only cooked 3-4 pieces at a time so that the oil temp remained as close to 360F as possible.
Carefully remove the fish sticks from the oil and drain them in some paper towels, continuing until all the fish sticks are cooked. If making a big batch, place the fish sticks on a wire rack after draining , this will help prevent them from getting soggy. You can optionally keep them in a 250-300F oven until you need them.
Warm up the corn tortillas in the oven for a few minutes, or nuke them in the microwave for 60 seconds. Each tortilla gets fried fish, Chipotle Crema, pickled cabbage, and a final squeeze of lime. Enjoy!