Cut the tomatoes into wedges and arrange them in a large dish. Chop the red onions finely and spread them over the tomatoes together with the basil leaves. Tear the mozzarella into small pieces and spread the pieces evenly over the tomatoes. Finish with some freshly-ground pepper. Make the dressing by mixing olive oil, balsamic vinegar, Heremesetas Liquid and sea salt in a bowl and stirring well. Pour the dressing over the tomato salad.