Cut the mozzarella into slices. Mix the vinegar, mustard, honey, garlic, salt and pepper together. Brush the mozzarella with it and let it steep for 30 minutes.
Cut the tomatoes into cubes, halve the avocado, remove the stone, remove from the skin and dice the pulp. Halve the rocket leaves once in the middle.
Mix lemon juice and oil. Put the mozzarella, tomatoes, avocado and rocket in a bowl, pour the oil mixture over them and mix.