Clean, wash and cut the rhubarb into pieces. Peel and chop the onions and fry them in hot oil. Sprinkle sugar over them and caramelize. Stir from time to time. Stir in vinegar and mustard. Add rhubarb and berries.
Season with salt and pepper. Simmer at low heat for about 30 minutes. Stir more often.
Season the chutney again and let it cool down. Serve with Brie and Comté. Bread rolls or wholemeal bread taste good with it.