Remove the skin and pit from the avocado, place the flesh in a bowl and mash with a fork. Season with lemon juice, olive oil, salt and pepper. Roughly chop the basil and fold into the avocado mixture. Slice the tomatoes and dice the drained mozzarella. Slice the bread and toast on both sides. Spread with avocado cream and top with tomato slices and mozzarella cubes. Season again with olivesseason with olives, salt and pepper.