Chop red bell pepper, red onion, and cilantro finely using a sharp knife on a clean cutting board. Measure out the chopped ingredients and set aside.
In a large mixing bowl, combine rinsed black beans, corn kernels, diced tomatoes, red bell pepper, red onion, and cilantro. Gently toss to evenly distribute the ingredients.
Juice the limes using a lime squeezer or juicer, removing seeds, and pour the lime juice over the mixture in the bowl. Add olive oil, ground cumin, salt, and pepper.
Use a large spoon to thoroughly toss the mixture, ensuring the lime juice and seasonings evenly coat all ingredients. The colors should appear bright and fresh, with a slightly glistening surface from the olive oil.
Let the Cowboy Caviar sit at room temperature for about 5 minutes to allow flavors to meld. Taste and adjust seasoning with additional salt, pepper, or lime juice if desired.
Serve the Cowboy Caviar in a serving bowl, garnished with extra cilantro if desired. It can be enjoyed immediately or refrigerated for later use.
