Heat oven to 450°Line a rimmed baking sheet with aluminum foil, or grease with cooking spray.
Use a sharp knife to lightly score of the fish lines about 1-inch apart.
then Brush the fish generously on both sides with the oil. Then briefly brush the inner cavity with oil as well.Slice half of the lemon into slices, and stuff those as well as the garlic into the cavity of the fish.Season the outside of the fish generously with a few good pinches of sea salt, black pepper and garlic powder.
In a large baking dish or rimmed baking sheet, lay the fish on its side and cook until lightly charred and cooked through, about 20 minutes, or until the fish reaches an internal temperature of 145°F and flakes easily with a fork. (Cooking time will vary depending on the size/variety of your fish.)
Remove from the oven, and squeeze the juice from and green scallions the remaining lemon half evenly over the top of the fish.Serve warm, and enjoy!