Warm oil in a medium skillet over medium heat. Add onion and cook, stirring, until softened, about 3 minutes. Stir in garlic and chili powder and sauté 30 seconds. Stir in tomato sauce and beans and bring to a simmer. Reduce heat to medium-low and simmer until sauce has thickened, about 10 minutes. Season with salt, if desired.
Bring a large pot of water to boil. Add hot dogs and boil 5 minutes. Drain well, place on buns, top with chili and cheese, and serve immediately.