Lentil Soup with Sausage, Chard and Garlic

Name: Lentil Soup with Sausage, Chard and Garlic
Cuisine: European, Mediterranean
Ingredients: 1/2 cup olive oil, divided; 2 large links (about 8 ounces) of sweet Italian sausage, casings removed [see Note]; 1 medium onion, diced; 2 celery ribs, sliced or diced; 2 medium carrots, peeled and sliced into half-moons or diced; 4 cloves garlic, sliced (reserve half for later in recipe); Kosher salt; A pinch of crushed red pepper flakes (optional); 1 cup brown lentils, sorted and rinsed; 2 bay leaves; 1 28-ounce can crushed tomatoes; 6 cups water; Freshly ground black pepper; 3 to 4 cups shredded or thinly ribboned Swiss chard leaves or kale; Grated Pecorino Romano cheese to finish