Wash the lentils and soak them overnight. Clean and cut the vegetables. Prepare the tomato and onion separately. Mash the garlic and ginger with a little salt and sugar in a mortar to a paste.
Heat the oil and fry the onions. Add the vegetables and the garlic and ginger paste and cook for about 5 minutes. Stir in the tomatoes and pour in the vegetable stock. Add the lentils and season with thyme, parsley, pepper and salt. Cook for about 1 hour.
Season again to taste and sprinkle with coriander before serving.