Prepare the ingredients for the recipe. When purchasing oysters, have the store open them up for you. If doing it yourself, pull oyster shells apart using an oyster knife. Discard the top shell and loosen the oyster meat using the tip of the oyster knife.
In a bowl, using a spoon, combine together the softened butter, miso, Sriracha and lime juice.
Leave the oysters inside the bottom shells and place them directly over the coals or the grill rack, facing upward; grill for approximately 3 minutes. Top each oyster with about 1/2 teaspoon of the miso butter mixture; use a bit more for larger oysters and less for smaller ones.
Place oysters back on the grill for an additional 3 minutes. Serve them right away with scallions and lime wedges.
Recipe Notes: Cooking temperature for Oysters: For your safety, please reference the USDA safe cooking temperatures.Tips for Oysters: Check to see if the oysters are alive by confirming that shells are tightly closed; discard any that are not tightly closed. Scrub oysters with a stiff brush under running water. Rinse well and refrigerate until ready to grill.