Heat olive oil in the pot or skillet under medium heat. Sauté the onion and carrot for 8-10 minutes, stirring until the onions are soft and start to brown. Add the garlic, curry powder, thyme and cook for another minute or so. Then add the lentils, tomatoes, stock and salt and pepper. Bring to a boil under high heat so all the flavors are released, then turn the heat down to low so the stew is just simmering gently when covered. Continue cooking for about 40 minutes or until the lentils are tender and most of the liquid has been absorbed. Add the sliced sausage, stirring so the stew is mixed well and let sit off the stove so everything settles and the sausage is warmed through. Add a dash of vinegar and stir in just before serving.