Coat a nonstick skillet with cooking spray; place over medium-high heat until hot. Add onion and next 3 ingredients; sauté until tender. Add tomatoes. Bring to a boil; reduce heat, and simmer, uncovered, 10 minutes, stirring occasionally. Add shrimp. Cover and cook 5 minutes or until shrimp are done.
To serve, spoon shrimp mixture over rice.