Boil the seaweed and capers in the water until the seaweed is soft. Transfer to a blender and blend into a paste. Fold the paste into the softened butter with the lemon juice. Refrigerate until needed.
Place the closed oysters on open hot coals. Lightly cook or just warm. The lids will pop up. Remove the lids and serve 2 oysters per portion with seaweed butter.
To assemble, plat