- 2 tablespoons cooking oil
- 1 onion, chopped
- 2 carrots, chopped
- 2 ribs celery, chopped
- 1 clove garlic, minced
- 1 pound lentils
- 2 1/2 quarts water
- 2 tablespoons tomato paste
- 1 bay leaf
- 2 1/4 teaspoons salt
- 1/4 teaspoon fresh-ground black pepper
- 1 pound broccoli rabe, cut into 1 1/2-inch lengths
- 1 1/2 lemons, zested
- In a large saucepan, heat the oil over moderately low heat. Add the onion and cook, stirring occasionally, until translucent, about 5 minutes. Stir in the carrots, celery, and garlic and cook, stirring occasionally, until the vegetables start to soften, about 5 minutes.
- Stir in the lentils, water, tomato paste, bay leaf, salt, and pepper. Bring to a boil. Reduce the heat and simmer, partially covered, stirring occasionally, until the lentils are tender, about 30 minutes.
- Meanwhile, in a large pot of boiling, salted water, cook the broccoli rabe until just tender, about 5 minutes. Drain.
- Stir the lemon zest into the soup. Remove the bay leaf. Ladle the soup into bowls and top each serving with some of the broccoli rabe.