This is a grilled version of a classic Filipino dish. Skin-on snapper is grilled and finished with julienned vegetables and a quick sweet and sour sauce that's filled with island flavors. If you're not a fan of snapper, feel free to substitute it with any white meaty fish.
Preheat a grill to medium high. Heat 2 tablespoons vegetable oil in a medium saucepan over medium heat. Add the garlic and ginger and cook, stirring, until softened, about 2 minutes. Whisk in the vinegar, pineapple juice, fish sauce, brown sugar and ketchup. Bring to a steady simmer and cook until reduced by almost half, about 10 minutes.
Meanwhile, combine the scallions and bell peppers in a medium bowl with the remaining 1 tablespoon vegetable oil. Season with salt and pepper and toss. Grill until well marked and tender, about 2 minutes per side for the scallions and 3 minutes per side for the peppers.
Score the skin side of the snapper fillets, making a few small slashes. Pat dry. Brush both sides of the fillets with vegetable oil and season with salt and pepper. Lightly oil the grill grates. Grill the fish skin-side down, covered, until it’s cooked around the edges, 3 to 4 minutes. Flip and cook through, 3 to 4 more minutes.
Cut the scallions into 3-inch pieces and cut the peppers into 1/4-inch strips. Divide the vegetables and fish among plates. Pour some of the sauce on top and serve the rest on the side. Serve with the rice.