Heat the chicken broth. Wash and inspect the lentils. Cut the onions and carrots into 1 cm pieces. Cut the sausages into 0.5 cm thick slices. Heat the oil in a large heavy saucepan over a medium heat.
Add the sausages to the hot oil and cook until browned (about 2 minutes). Take the sausages off the heat and put them on a paper towel.
Add the onions and carrots to the fat and cook until they are soft - about 10 minutes.
Add the garlic and tomato paste, reduce the heat and continue stirring for about 1 minute.
Add the lentils, increase the heat to medium, and return the sausages to the pan while stirring for a couple of minutes until the lentils are properly mixed with the fat and vegetables.
Pour in the broth, add the thyme and the bay leaves, cover, bring to a boil and cook until the lentils are soft (about 40 minutes).
Season with salt and pepper to taste. Serve with toast.