Preheat oven to 400 degrees F (200 degrees C). Place oysters in a baking pan, flat-side up.
Stir butter, sriracha sauce, garlic, green onions, cilantro, and lime juice together in a bowl.
Bake oysters in the preheated oven until they open slightly, about 10 minutes.
Remove the top shell of the oysters using a towel and an oyster knife, being careful not to spill the liquor. Gently cut the muscles that attach the oysters to the shell.
Divide the butter mixture among the oysters, placing a dollop on each. Sprinkle Parmesan cheese on top.
Set oven rack about 6 inches from the heat source and preheat the oven's broiler.
Broil oysters in the preheated oven until butter melts and Parmesan cheese is golden brown, about 5 minutes.
