Cook and stir ground beef and onion in large skillet until meat is brown and onion is tender.
Stir in garlic, 1 1/2 cups water, the soy sauce and molasses; heat to boiling.
Add green beans and heat to boiling.
Reduce heat; simmer uncovered 15 minutes.
Blend cornstarch and 1/4 cup cold water; stir gradually into meat mixture.
Cook, stirring constantly, until mixture thickens and boils.
Boil and stir 1 minute.
Serve over rice; garnish with onion rings.
If desired, pass additional soy sauce.