1Cook tortellini as directed on package; drain, reserving 1/4 cup cooking water.
2Meanwhile, in 12-inch skillet, heat oil over medium heat. Add garlic; cook and stir 30 seconds. Add tomatoes; cook 3 to 5 minutes, stirring occasionally, until tomatoes begin to split (gently press tomatoes down with spatula or back of spoon).
3Add tortellini and reserved cooking water to skillet. Cook 2 minutes. Top with green onion.