Pound together the walnuts and garlic in a mortar. If you have no mortar, you can short-cut the process a little with the aid of a food mixer. If the garlic and walnuts are fresh and juicy, it will grind them fairly finely and you can finish them off in a bowl with the aid of the thick handle of a wooden spoon. You need to get as finely-ground a mixture as possible.
Stir in one or two t