Garlic Sausage With Green Lentils

Name: Garlic Sausage With Green Lentils
Ingredients: 4 clv garlic, peeled and left whole; 4 sprigs thyme; 4 bay leaves; 3 garlic sausages, 2 inches in diameter and 11 inches long; 4 leeks, 2 cleaned and halved lengthwise, 2 cleaned and roughly chopped; 4 carrots, 2 halved lengthwise, 2 diced into 1/4-inch cubes; 0.5 t whole black peppercorns, plus 6 extra for the glazed onions; 1 c red pearl onions; 1 c white pearl onions; 2 t sugar; 0.25 t kosher salt; 2 T unsalted butter; 3 T red wine vinegar, separated 2 plus 1; 2 T olive oil; 0 salt and pepper to taste; 16 oz french green lentils; 0.25 c chives, chopped as garnish