In a large bowl, combine the black beans, kidney beans, corn, red bell pepper, red onion, cilantro, and jalapeño if using.

In a small bowl or jar, whisk together the olive oil, lime juice, lime zest, apple cider vinegar, honey or maple syrup, cumin, salt, and black pepper until well blended.

Pour the dressing over the bean mixture and toss gently to coat everything evenly.

Cover and refrigerate for at least 30 minutes to allow the flavors to marinate, stirring once or twice if desired.

Just before serving, gently fold in the diced avocado.

Taste and adjust seasoning with a little more salt or lime juice if needed, then serve chilled or at room temperature.