Heat oil in a pan over medium-high heat; add ground beef and brown, about 5 minutes. Drain excess fat and add taco sauce. Simmer 2 minutes, remove from heat and set aside to cool.
Prepare a 15 x 10 x 2-inch baking dish by spreading the refried beans on the bottom in one consistent layer. Continue to layer with black beans, green chilies and reserved beef.
Cover with foil and bake 30 minutes to heat all layers. Remove from oven, top with shredded cheese, allowing cheese to melt slightly.
Using a spoon, dollop sour cream evenly on surface of cheese and gently smooth it across the top. Top with salsa and serve with chips.
Notes
Recipe and photo courtesy of Certified Angus Beef.