In a mixing bowl, combine the black beans, corn, red onion, red bell pepper, cilantro, lime juice, cumin, salt, and black pepper. Stir until everything is evenly mixed.
Spread the bean and corn mixture into a shallow serving dish and smooth the top with the back of a spoon.
Place the sour cream in a small zip-top bag and snip off one corner to create a piping tip. Pipe the sour cream in a spiral pattern over the dip.
Use a toothpick or knife to drag lines from the center outward, forming a spiderweb design.
Serve the dip with tortilla chips on the side.