Prepare rice according to package directions; cool. In a large skillet, heat oil over medium heat. Add ham and onion; cook and stir until onion is tender, about 5 minutes. Add next 6 ingredients; cook and stir 2 minutes. Remove from heat; stir in vinegar., Combine rice, ham mixture, shrimp, celery and peppers. Refrigerate, covered, at least 2 hours. Add tomatoes; toss to combine. Sprinkle with green onions.