Stir 1 cup onion, ¼ cup cilantro, 3 tablespoons lime juice, 3 tablespoons orange juice, garlic and oregano in a medium bowl. Sprinkle fish with coarse salt and pepper.
Spread half of the onion mixture over the bottom of a baking dish large enough to fit your fish. Arrange fish atop the mixture and spoon mixture over the top of fish. Cover and chill for 30 minutes. Flip fish and chill for 30 minutes more.
Whisk the mayonnaise or yogurt, milk, and remaining 2 tablespoons of lime juice in a small bowl.
Oil and prepare your grill to medium high heat. Grill fish until just opaque in the center for about 3-5 minutes per side. Grill your tortillas as well, about 10 seconds per side.
Coarsely chop your fish and serve in tortillas. Top with the lime, mayonnaise, onion, cilantro, cabbage, salsa and lime wedges.

Recipe courtesy of and adapted from the Pacific Fishery Management Council.
Photos courtesy of Lauren Allen of Tastes Better from Scratch, and Alaska Seafood Marketing Institute.