Divide the mozzarella among the pizza crusts. Top with the sliced tomatoes or halved cherry tomatoes. Cook until the cheese is melted, about 5 minute on the grill.

In a medium mixing bowl, combine the olive oil, lemon juice, ½ teaspoon salt, and ¼ teaspoon pepper. Add the arugula and toss to coat. Divide the arugula among the pizzas and top with grated parmesan cheese plus an extra pinch of salt and pepper.