Finely dice the onion and garlic and sauté briefly in a pan with 1 tbsp. olive oil. Stir in the lentils and tomato purée, pour in the vegetable soup. Add the tomatoes and simmer the sauce for approx. 20 minutes until the lentils are cooked. Stir occasionally. Cook the spaghetti in salted water until al dente according to the packet instructions. Flavour the lentil bolognese with salt and pepper. Drain the spaghetti and leave to drain briefly, arrange on plates and pour over the bolognese. Grind over the pepper and sprinkle with the Parmesan. Garnish with basil leaves.