Heat 2 teaspoons oil in a soup pot or Dutch oven over medium heat. Add onions and cook, stirring, until softened, 3 to 5 minutes. Add garlic and cumin; cook for 1 minute. Add broth, lentils, bulgur, tomato paste and bay leaf; bring to a simmer, stirring occasionally. Cover and cook over low heat until the lentils and bulgur are very tender, 25 to 30 minutes. Discard the bay leaf.