By Jane Grigson
Allow about eight oysters or ten mussels or clams per person, depending on their size and the rest of the meal. The remains of the garlic butter can be stored in the refrigerator and used with lamb, chicken, potatoes, beans and so on.
Open the oysters or clams with an oyster knife or the mussels by steaming them according to the method. Discard one shell, choosing the flatter one, in the case of oysters, from each.
If you have a food processor, whizz the garlic, shallots and parsley to a speckled crumble. Alternatively, chop them together very finely. Add the butter to the garlic mi