Heat oil in a medium, deep skillet. Saute onions for 3-5 minutes. Add tomato sauce and cook for another 5-7 minutes, stirring occasionall to prevent burning.
Add 1 cup of water , all remaining ingredients except the rice and beans. Cover and let simmer for about 10 minutes.
Triple wash rice with warm water. Add into skillet together with beans, 2 more cups of water. Adjust seasoning if necessary. Seal skillet tightly (with foil then lid). Reduce heat to medium and cook for 25 minutes until all liquid is absorbed. Remove from heat, let stand for 5 minutes, fluff and enjoy.