Add onions and olive oil to a large heavy bottomed pot over medium heat. Stir and cook for a few minutes until softened.
Add cumin and garlic and stir to toast spices for 2 more minutes.
Stir in pinto beans then add broth and salt and bring to a simmer over low heat for about 30-40 minutes depending on the consistency you're going for. If you want more jammy beans, go for 40 minutes. If you want them more whole, simmer for 30 minutes.
Taste and season with more salt if needed before serving.