1. Start with the veggies – peel and finely dice the onion and garlic. Clean the carrots and celery and cut them into small pieces. Clean the leek and cut it into rings – wash well and let soak in water for a while to get rid of any sand between the layers. Let drain. Clean the potatoes, peel them if needed (many types of potatoes can be eaten with the skin on), and cut them into smaller (but not too small) pieces. Set everything aside.

2. Heat up a Dutch oven (or large pot) with some olive oil. Add the onion and garlic and sauté until soft and glossy. Add the diced carrots, celery, and leek – fry briefly. Rinse the lentils with cold water. Add to the Dutch oven together with the tomato purée and the dried thyme – mix well and let cook/fry for 1-2 minutes until fragrant. Deglaze with the veggie stock and add the bay leaf. Cover the stew, reduce the heat, and let it simmer for about 10 minutes. Next, add the potatoes and let the stew cook/simmer for another 20 minutes (also covered). The potatoes should be cooked through, but the lentils should not be completely mushy.

3. Season the stew well with salt and pepper, remove the bay leaf, then divide between bowls and garnish with some chopped parsley. Serve the stew with the vinegar on the side, so everyone can season the dish with the vinegar to their liking.