Step 1: Cook the pancetta until crispy then set aside on kitchen paper to drain.

Step 2: Slice the mozzarella into one centimetre discs and marinate for a few minutes with the lemon zest, lemon juice, salt flakes and freshly ground black pepper.

Step 3: Flatten the slices of bread using a rolling pin, trim off the crusts and then butter each slice thinly. Place two of the slices, butter side down on top of a chopping board and divide the marinated mozzarella between them. Add the torn basil leaves, salt to taste and the crispy pancetta. Top with the other slice of bread – butter side facing up and gently fry the sandwiches in a heavy based frying pan over a moderate heat until they are golden on both sides. Remove and slice into three fingers and serve.