Place sliced tomatoes in a colander in the sink. Sprinkle with salt and stir to coat. Every 10 minutes or so, just give it a gentle stir to release more water. Pour out onto paper towels and roll them around gently to remove as much moisture as possible. The salt will draw out the excess water from the tomatoes so when you add them to the cheese, it won’t be watery. Don’t skip this step.