Add the beluga lentils to the slightly boiling water. Cook over medium heat until al dente, about 20 minutes, and season with salt just before the end of cooking time. Drain in a colander to cool and drain well. Cook the red lentils for 8-10 minutes until al dente, adding salt just before end of cooking time. Drain in a colander to cool and drain well.
Finely chop the onion. Wash carrots, celery, and Jerusalem artichoke, peel and cut into 1cm pieces.
Finely chop the onion. Wash carrots, celery, and Jerusalem artichoke, peel and cut into 1cm pieces. 3. Melt the butter in a saucepan and fry the onion over medium heat for 3-4 minutes. Add carrots, celery and Jerusalem artichoke and saute for another 3-4 minutes, seasoning with salt and pepper. Add curry and steam for a while, then fill with stock. Cook on low heat for about 25 minutes. Add the red lentils and boil for about 2 minutes. Finely puree 250ml stew in a tall container with a fork. Then puree the stew.
Pick the mint leaves and set aside. Heat the stew and heat the beluga lentils. Serve the lentil stew with mint leaves immediately on a preheated plate. Serve the vinegar separately.