1. In a large pot or Dutch oven, heat the olive oil over medium-high heat. Add the celery, carrot, onion, and garlic, and cook for 5 to 6 minutes until tender.

2. Add the water, lentils, cumin, and kosher salt. Bring to a simmer and simmer for 30 minutes until the lentils are tender (if not tender, keep cooking a few more minutes). Taste and add additional salt to taste (we usually add another 1/2 teaspoon) and freshly ground black pepper.

3. Serve immediately with grated Pecorino Romano cheese if desired, or refrigerate for meal prep. The soup lasts up to 1 week refrigerated, and leftovers taste even better (you can also freeze them for up to 3 months). Leftovers may soak up extra broth, so you can add a splash of water and a pinch of salt if the texture becomes too thick.