A thick stew made with Le Puy lentils and kielbasa makes ahearty, no-fuss meal. Its aroma, reminiscent of French country cooking, comes from a blend of bay leaf and rosemary.
Heat 2 tablespoons oil in a large saucepan over medium-high heat until hot but not smoking. Brown sausage, about 6 minutes. Transfer to a bowl.
Add onion, carrots, celery, and garlic to pan; cook, stirring occasionally, until softened, about 5 minutes.
Stir in the lentils, stock, 3 1/2 cups water, bay leaf, 1 teaspoon rosemary, and remaining 2 tablespoons oil; season with salt. Bring stew to a boil. Reduce heat to medium-low, and simmer until lentils are just tender, about 50 minutes.
Return sausage to the pan; cook until heated through, about 5 minutes. Stir in remaining 2 teaspoons rosemary. Season stew with salt and pepper.
If making ahead, reheat over medium-low heat, stirring occasionally and thinning with a bit of water, if needed.