Prepare the Lime Crema: In a small bowl, mix together the sour cream, mayonnaise, lime juice, lime zest, and a pinch of salt. Adjust seasoning if necessary. Set aside in the fridge to chill while preparing the tacos.
Season the Fish: In a bowl, combine cumin, paprika, garlic powder, salt, and black pepper. Rub the spice mixture evenly over the fish fillets.
Cook the Fish: Heat olive oil in a skillet over medium heat. Once hot, add the seasoned fish fillets. Cook for about 3-4 minutes on each side, or until the fish flakes easily with a fork. Remove from heat and let it rest for a minute before flaking it into bite-sized pieces.
Warm the Tortillas: In a separate skillet, warm the corn tortillas over medium heat for about 30 seconds on each side until they're pliable.
Assemble the Tacos: On each tortilla, layer some flaked fish, shredded red cabbage, sliced avocado, and fresh cilantro. Drizzle the chilled lime crema over the top.
Garnish and Serve: Serve the tacos with lime wedges on the side for an extra burst of flavor.