Drain and rinse black beans under cold water, then place them in a large mixing bowl.
Dice avocados and add them to the bowl, being careful not to over-mash.
Dice cherry tomatoes and finely chop red onion and jalapeño (if using). Add them to the bowl.
Chop fresh cilantro and sprinkle over the mixture.
Add lime juice, ground cumin, salt, and black pepper.
Gently toss all ingredients until evenly combined.
Taste and adjust seasoning as needed.
Optional: Cover and refrigerate for 10–15 minutes to let flavors meld.