This is a rustic, satisfying lentil soup made with basic ingredients, including dried brown or green lentils, Italian-style seasonings and canned tomatoes. It really delivers on flavor and is so good to stash in your fridge for a simple meal.
Place a large, heavy pot (such as a Dutch oven) over medium heat. Add the olive oil, onion and celery and stir. Cover the pot and cook 5 minutes to soften the vegetables.
Stir in the garlic, tomato paste, oregano and red pepper. Cook for about 15 seconds, until aromatic. Add the lentils, tomatoes, 5 cups broth, 2 teaspoons salt and black pepper to taste. Toss in the bay leaf and cheese rind, if you're using.
Turn the heat up to medium-high until the liquid comes to a boil. Reduce the heat to a simmer and cook uncovered 30-35 minutes, stirring occasionally, until the lentils are tender and the soup looks thickened. If the lentils are older, they may take up to 45 minutes. Remove the rind and bay leaf and discard.
Scoop out a generous cup of the soup and puree in a blender. You can also briefly pulse a hand blender right in the pot. At this point, you can add the remaining cup of broth if the soup seems too thick.
Add the vinegar and parsley to the soup and stir. Taste the soup and add more salt and pepper, if needed. Serve the soup warm in bowls, with some grated cheese over each portion. Add a side of warm crusty bread for dipping!
Notes
The soup will keep up to 5 days in the refrigerator and 1-2 months frozen.
Depending on the age and freshness of your lentils, their cooking time can vary. To cut down on cooking time, you can briefly soak the lentils while you're prepping other ingredients.
Serving ideas: Stir in a big handful of greens (spinach, chopped kale, etc.) until wilted. Add about a cup of cooked pasta, such as orzo or tiny shells.