Brown ½ pound ground beef in a large skillet over medium-high heat, breaking it apart as it cooks. Drain any excess grease.
Add ½ diced red onion to the skillet and sauté for a few minutes until softened.
Stir in 1 can (14.5 oz) diced tomatoes with green chilies and 1 cup thawed frozen corn kernels. Cook for 2 minutes.
Reduce the heat to low. Add 16 ounces cubed Velveeta cheese, 4 ounces diced cream cheese, 1 cup shredded pepper jack cheese, and ¼ cup milk. Stir constantly until all the cheese is melted and the mixture is smooth.
If the queso becomes too thick, add additional milk 1 tablespoon at a time until the desired consistency is reached.
Stir in 1 cup black beans (drained and rinsed) and most of the ¼ cup chopped fresh cilantro, reserving some cilantro for garnish.
Serve warm topped with the remaining cilantro.
Notes
Cube the Velveeta into small pieces for faster, more even melting.The queso will thicken as it cools. Keep it warm over low heat, stirring occasionally, and add milk as needed to maintain desired thinness.