Heat oven to 200F. In a a skillet heat oil over medium heat. Stir in onion, cook 3 minutes. Add garlic, chili powder, cumin, and 1/4 tsp. of the salt, cook another 2 minutes. Stir in beans and broth, bring to a simmer and cook 3 minutes. Smash half the beans with the back of a fork and stir. Place tortillas on a baking sheet and spread 2 Tbsp. of the beans on each tortilla. Place in the oven.