Heat large saute pan on stove at medium-high heat. Reduce heat to medium, add olive oil and garlic. Saute for a minute, then add okra, tomato sauce and water. Reduce heat to low, cover and allow to simmer for 10 minutes, until okra becomes softened. Add black beans. Cover, cook on low another 5 minutes. Add corn kernels. Cover and cook on low another 5 to 10 minutes until corn cooks. Uncover and add cooked rice, mixing to blend inches Remove from heat and add cooked shrimp. Top with finely chopped cilantro and onion, if desired.