Step 1: Prepare the vegetables. Dice the Roma tomatoes, finely dice the red onion, and dice the green, red, and yellow bell peppers into small, uniform pieces. Chop the fresh cilantro. If using, seed and mince the jalapeño.
Step 2: Combine the main ingredients. In a large mixing bowl, combine the rinsed and drained black beans, pinto beans, and drained sweet corn. Add the diced tomatoes, red onion, green bell pepper, red bell pepper, yellow bell pepper, chopped cilantro, and minced jalapeño (if using).
Step 3: Whisk the dressing. In a separate small bowl, whisk together the olive oil, lime juice, apple cider vinegar, minced garlic, ground cumin, chili powder, salt, black pepper, and optional pinch of cayenne pepper until well combined.
Step 4: Dress the caviar. Pour the dressing over the bean and vegetable mixture in the large bowl.
Step 5: Toss to combine. Gently toss all the ingredients until everything is thoroughly coated with the dressing.
Step 6: Chill and serve. For best flavor, cover the bowl and refrigerate the cowboy caviar for at least 30 minutes to allow the flavors to meld. Serve chilled with tortilla chips, as a side dish, or as a topping.