In a saute pan over medium heat, add olive oil. When hot, add onion and bell pepper. Cook for 3-4 minutes, or until vegetables begin to brown around the edges.
Add black beans, salsa, pasta, taco seasoning, vegetable broth, and milk to pan. Stir to combine. Bring to a boil, cover, and reduce heat to low. Simmer according to your pasta's package directions for al dente pasta (my bow tie pasta took 12 minutes). Once pasta is cooked through, most of liquid in pan should be absorbed.
Add sour cream and shredded cheese to pan, stirring until cheese is melted. Remove from heat and allow to set for 5 minutes to allow sauce to thicken before serving.
Notes
Any medium sized pasta can be used (macaroni, shells, or penne).
Because the entire dish is cooked in a single pan, it is extremely important to use exact measurements for your liquids (broth and milk) and pasta. Recipe is written to include just enough liquid to cook pasta through without leaving excess liquid in the pan.
Leftovers will keep for 3-4 days in a sealed container in the refrigerator.