Peel the onions and cut off the lid. Hollow out the onions. Finely chop the onion interior. Heat oil in a pot. Fry half of the chopped onions in it until transparent. Add millet and 1/4 litre stock.
Bring to the boil, cook for 20 minutes, let cool. Wash parsley, chop finely except for a little bit for garnishing. Cut cheese into small cubes. Mix millet, parsley and cheese. Season to taste with salt and pepper. Put onions in a casserole dish, add millet. Pour on 1/4 litre of stock and cook in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 30 minutes. Clean, wash and dice the peppers. Heat the fat in a pot. Sauté the bell peppers and remaining onions in it. Dust with flour. Stir in the Aivar and 1/4 litre stock and simmer for 5 minutes.
Clean, wash and dice the peppers. Heat the fat in a pot. Sauté the bell peppers and remaining onions in it. Dust with flour. Stir in the Aivar and 1/4 litre stock and simmer for 5 minutes. Season to taste with salt and pepper. Arrange the onions with the sauce on plates. Serve garnished with parsley