"Sweet and spicy, snapper holds up really well to this cooking, but feel free to use a fish of your liking. Also you can just use fillets instead of whole fish, but for wow factor whole fish is the way. Serve with rice."
Cut heads off each snapper and score skin on each side; sprinkle with sea salt.
Heat 2 tablespoons vegetable oil in a large skillet over medium heat. Add snapper and pan-fry until skin is brown and crispy and flesh flakes easily with a fork, 6 to 8 minutes per side. Place snapper on a serving platter and return skillet to stove top.
Cook remaining oil, tomatoes, chiles, and garlic over high heat in a skillet until tomatoes soften, 2 to 3 minutes. Add water, fish sauce, and palm sugar; simmer until mixture is reduced slightly, 1 to 2 minutes. Stir in green onions, cilantro, and cornstarch; simmer until mixture is reduced to a sticky-sauce consistency, about 1 minute more. Pour sauce over fish to serve.