Barefoot Contessa | Lentil Sausage Soup (updated)

Ingredients

• 1 pound French green lentils, such as le Puy
• 1⁄4 cup good olive oil, plus extra for serving
• 4 cups chopped yellow onions (2 to 3 onions)
• 4 cups chopped leeks, white and light green parts (2 leeks)
• 1 tablespoon minced garlic (2 large cloves)
• 1 tablespoon minced fresh thyme leaves
• 1 teaspoon ground cumin
• Kosher salt
• freshly ground black pepper
• 3 cups medium-diced celery (8 stalks)
• 3 cups medium-diced carrots (4 to 6 carrots)
• 3 quarts (12 cups) chicken stock, preferably homemade
• 1⁄4 cup tomato paste
• 1 pound kielbasa, cut in half lengthwise and sliced 1⁄3-inch thick
• 2 tablespoons red wine vinegar
• Freshly grated Parmesan cheese, for serving