PLACE arugula, pine nuts, garlic and salt in food processor; process until finely chopped. Add oil; process until combined. Add cheese; pulse to combine.
PREPARE pasta according to package directions, reserving 1/4 cup of cooking water.
TOSS pesto with pasta; thin with reserved cooking water, if desired.
PLACE a few slices of tomatoes on each plate; top each with about 1 cup of pesto tortelloni. Season with pepper. Drizzle with extra oil and sprinkle with additional pine nuts, if desired.
