In a large bowl, combine the tomatoes, mozzarella cheese, basil, parsley and mint. Give everything a good toss, then set it aside.
In a small bowl, whisk the lemon juice, olive oil, salt and pepper. Pour the dressing over the tomato mixture, and toss to coat. Cover and refrigerate for at least one hour before serving.
Just before serving, pit and cube two ripe avocados. Add them to the bowl and gently toss, being careful not to mash the avocado too much. Serve the salad with a slotted spoon, and enjoy!
