Put the tomato into a bowl, add a good pinch of salt and a tablespoon of olive oil.In a separate bowl, mix the salad leaves with the mayonnaise, lemon juice and a good pinch of black pepper.
Allow both the tomato and the salad leaves to sit while you prepare the bacon and bread – it’s vital that you do this first to allow the tomato to stand in the salt and the lettuce to wilt a little with the mayonnaise.
Put the rashers of bacon on top of each slice of bread. Whack them under the grill on a medium heat – cooking the bacon slowly means that the bacon juices run out on to the bread. It also makes the bacon very crisp.
When the bread is toasted, remove it from the grill and put to one side. Turn the bacon and cook for a further 3 to 4 minutes.
Place the cooked bacon rashers onto a slice of toasted bread. Cover with a handful of the lettuce and scoop over the tomatoes with all the juices.
Smear the mustard over the other piece of bread. Place on top of the sandwich, squeeze down, cut in half and enjoy.