Swirl olive oil in a skillet to cover the bottom; place over medium heat. Add onion, garlic, and cayenne pepper; cook and stir until fragrant, about 1 minute. Add green pepper and cook until tender, about 5 minutes.

Stir in frozen okra and cook for 5 minutes. Stir in both stewed and diced tomatoes, then season with salt and pepper. Reduce the heat to medium-low and simmer until all vegetables are heated through and tender, 5 to 7 minutes.