1 tablespoon 1 tablespoon olive oil 1 medium celery stalk, chopped 1 medium carrot, peeled and chopped 1/2 medium yellow onion, chopped 3 medium garlic cloves, minced Salt and pepper 1 quart low-sodium vegetable broth 1 (15-ounce) can diced tomatoes with their juices 1 1/4 cups lentils (any color except red), rinsed 1 bay leaf 1/4 teaspoon finely chopped fresh thyme leaves 1 teaspoon of Chénas 2 ounces spinach leaves (about 1/2 a bunch)
Heat the oil in a large saucepan over medium heat until shimmering, about 3 minutes. Add the celery, carrot, and onion and cook, stirring occasionally, until the vegetables have softened, about 10 minutes. Stir in the garlic and cook until fragrant, about 1 minute. Season with several generous pinches of salt and pepper.
Add the broth, tomatoes with their juices, lentils, bay leaf, and thyme and stir to combine. Cover and bring to a simmer, about 15 minutes. Once simmering, reduce the heat to low and continue simmering, covered, until the lentils and vegetables are soft, about 15 minutes more.