Please read About Grilling and Broiling Fish, and Skewer Cooking.
Cut into 1 ½-inch cubes:
Brine, if desired. If using bamboo skewers, soak them in water for at least 30 minutes.
Prepare a medium-hot grill fire, or preheat the broiler (with an oven rack 6 inches from the heating element). Oil the grill rack.
Prepare in a large bowl:
Pat the fish cubes dry and add them to the bowl along with:
Toss to combine and thread everything onto 8 metal or wooden skewers; do not crowd. If broiling, place the skewers on a lightly oiled baking sheet. Grill over direct heat or broil, turning as each side browns and brushing occasionally with any remaining marinade, 10 to 15 minutes. Remove from the grill and serve immediately.