Fennel's mild flavor is similar to anise. It's especially compatible with sausage and pork.
Reserve some of the fennel leaves to garnish the soup. Chop enough of the fennel bulbs to measure 2 cups.
In a Dutch oven, heat olive oil over medium heat. Add garlic; cook and stir for 1 minute. Add onion; cook until golden brown, stirring occasionally. Add the 2 cups fennel and the carrot; cook until tender, stirring occasionally. Add the water, lentils, salt, and pepper. Bring to boiling; reduce heat. Simmer, uncovered, for 25 to 30 minutes or until lentils are tender.
Meanwhile, in a large skillet, cook sausage until browned. Using a slotted spoon, transfer sausage to lentil mixture. Stir in vinegar. Garnish with the reserved fennel leaves. Makes 10 servings.