Drain and rinse black beans and corn in a colander.
Remove stem and seeds from red pepper, then chop red pepper flesh into small pieces.
Peel red onion half and finely chop.
Cut off stem of jalapeño pepper and cut in half lengthwise. Use your knife to remove the seeds and most of the white membrane. Finely chop remaining jalapeño flesh.
Add black beans and corn to a large mixing bowl, then stir in chopped red pepper, red onion, jalapeño, garlic powder, kosher salt, lime juice, olive oil, and cilantro.
Let rest for 30-60 minutes to allow flavors to meld before serving.
