Heat oil in large skillet on medium-high heat. Add peppers; cook 7 minutes, stirring constantly. Stir in garlic; cook 1 minute. Add rice, water and barbecue sauce; stir. Bring to boil, stirring constantly. Top with chicken, tomatoes and cheese; cover. Simmer on medium-low heat 10 minutes or until rice is tender and cheese is melted. Top with onions.