Step 1: Begin by preparing all your fresh vegetables. Finely dice the red onion, red bell pepper, green bell pepper, and jalapeño (if using). If you find raw red onion too strong, soak it in cold water for 10 minutes, then drain and pat dry to mellow its flavor.
Step 2: Drain and rinse the canned black beans and corn thoroughly under cold running water until clear. Gently pat them dry to remove excess moisture, which prevents a watery dip.
Step 3: In a large mixing bowl, combine the rinsed black beans, corn, diced bell peppers, red onion, chopped Roma tomatoes, and fresh cilantro. Toss gently to mix.
Step 4: In a separate small bowl, whisk together the olive oil, freshly squeezed lime juice, minced garlic, ground cumin, chili powder, and season with salt and black pepper to taste. Adjust seasonings as desired.
Step 5: Pour the prepared dressing over the vegetable mixture. Toss everything gently until all ingredients are evenly coated. Cover the bowl and refrigerate for at least 30 minutes to allow the flavors to meld and deepen.
Step 6: Just before serving, dice your ripe avocado and gently fold it into the chilled cowboy caviar. Give it a final taste test and adjust any seasonings if needed. Serve immediately with tortilla chips or as a versatile topping.