Heat the oil in a heavy saucepan over medium-high heat. Add the onion and cook, stirring, until slightly wilted, 3 or 4 minutes. Add the garlic; stir for a few moments, or until aromatic.
Stir in the lentils and broth and bring to a boil. Lower the heat to maintain a steady simmer. Cover the pan and cook without stirring for 25 minutes. (Check occasionally to b