Preheat your outdoor grill to medium-high heat.
Roll each ear of corn in a damp paper towel. Microwave 2 minutes. Brush olive oil on each ear of corn.
Brush the fish with olive oil and season with garlic salt and paprika.
In a bowl, stir together the crema sauce ingredients.
Brush the grill grates with some olive oil. We'll grill the corn and the fish at the same time. Add the corn onto the grill (rotate frequently during cooking). Grill the fish for 3 minutes each side, taking care not to overcook the fish. During the last minute of grilling, throw the corn tortillas on the grill, flipping halfway.
Using a serrated knife, cut the kernals off the corn. Assemble tacos with cabbage, a piece of fish, a spoonful of sauce, corn, tomato, a squeeze of lime and a sprinkling of pepitas.