Prepare the vegetables: Rinse and fully drain the black beans and corn. Finely dice the red onion, red bell pepper, and jalapeño (if using).

Whisk the dressing ingredients together in a small bowl: Combine the olive oil, red wine vinegar, chopped cilantro, cumin, salt, and pepper. Whisk vigorously until well emulsified.

Combine the main components: In a large mixing bowl, gently combine the drained beans, corn, diced red onion, red bell pepper, and jalapeño.

Dress and chill: Pour the prepared dressing over the bean and vegetable mixture. Fold gently until everything is evenly coated. Cover the bowl and refrigerate for at least 30 minutes to allow the flavors to meld. (Can be refrigerated for up to 2 days.)

Final preparation and serving: Just before serving, dice the avocado and gently fold it into the caviar. Taste and adjust seasoning, adding more salt or lime juice if desired.

Serve chilled or at room temperature with tortilla chips, as a topping for grilled chicken, or alongside tacos.