Cut asparagus into 1-inch pieces. Chop the green onion.
Bring a large pot of water to boil over high heat. Add rigatoni and cook for 6 minutes. Add asparagus to the pot and continue to cook for an additional 3-4 minutes, until pasta is barely tender and asparagus is tender-crisp.
Drain pasta and asparagus, rinse with cold water, and drain well.
Return pasta and asparagus to pot. Add marinara sauce, sour cream, vinegar, onion, basil, salt and pepper. Toss to mix well. Heat 2-3 minutes until heated through.