Dampen the pita bread under the tap and squeeze dry very well in the palms of your hands.

Pound the garlic, walnuts, and a little salt in the mortar with the pestle and add the bread or hot potatoes, a few pieces at a time. Continue pounding, drizzling in the olive oil, lemon juice, and vinegar to form a thick, mealy paste. Add the remaining bread and/or potato as you go. Either serve at room temperature or chilled.