1 Make the salsa: In a bowl, mix together all salsa ingredients, except for the sugar, and refrigerate for at least 30 minutes or up to 2 days.
Taste and add sugar or additional seasonings to taste when ready to serve.
2 Heat the grill. If you have a gas grill, make sure to preheat it for at least 10 minutes with the lid closed. If you have a charcoal grill, push the coals to one side to make high heat and lower heat zones for cooking.
3 Prepare the fish: Remove fish from the refrigerator and pat dry with paper towels.
In a small bowl or jar, mix spices until completely combined. Brush the fish with a little oil, then sprinkle all over with seasoning.
4 Oil the grill: When your grill is hot, wipe the grates with oil. You can either use a grill brush or a small wad of paper towels dipped in the oil. Wipe the grates 5 to 10 times until they look black and glossy.
5 Grill the fish: Place your fish, skin side down, on the grill. If using a charcoal grill, place over indirect heat. On a gas grill, turn the heat down to medium (about 350F) and close the lid.
Grill until the fish is cooked through and flakes easily with an internal temperature of 145F.
Transfer the fish to a plate to rest.
7 Serve: Cut the fish into several pieces. Serve on tortillas, topped with salsa and other toppings.