Place the fish in a resealable bag or container. Combine the beer, chili powder, brown sugar, salt, cumin, garlic and lime zest and juice in a large bowl. Give it a good stir and pour it over the fish. Marinate the fish for 30 minutes in the refrigerator.
Preheat a grill or grill pan over medium-high heat.
Take the fish out of the marinade and pat dry completely. Brush the fish with the oil and grill until browned, 3 to 4 minutes per side. Transfer to a plate, cover with foil and let rest for 5 minute. Slice each fillet into slices.
Heat the tortillas on the grill for about a minute, or wrap them in a damp towel and microwave until warm, soft and pliable, about 1 minute.
Spread some of the Carlsbad Cream onto the warmed tortillas. Place a few slices of fish on top of each and then top with some cabbage and Pickled Red Onions. Serve with lime wedges on the side.
Carlsbad Cream:
Combine the sour cream, mayonnaise, hot sauce, salt and lime zest in a medium bowl and stir. Cover and refrigerate until ready to use.
Pickled Red Onions:
Yield:2 cups
Whisk the vinegar, sugar and salt together in a mixing bowl until the sugar and salt have dissolved. Add the oregano and onions, cover and allow to rest for 2 hours. Store in a jar or resealable glass container in the refrigerator for up to a month.