Preheat oven to 190°C/375°F. Grease loaf pan and dust with breadcrumbs. Peel and finely dice some of the onions and carrot. Finely chop walnuts. Crumble white bread. Add ground flaxseed and water to a small bowl and stir to combine.
Melt margarine in a frying pan. Add chopped onions and carrots and fry on medium-low heat for approx. 7 – 8 min. Add some flour and fry for approx. 1 – 2 min., then deglaze with plant-based milk. Season with parsley, thyme, and marjoram. Let slightly thicken while stirring. Season with salt and pepper to taste.
Heat oil in a frying pan. Add vegetarian ground meat and fry for approx. 3 – 4 min. Set aside.
Add fried vegetarian ground meat, fried onions and carrot, ground hazelnuts, chopped walnuts, crumbled white bread, mustard, some tomato paste and flaxseed mixture to a large bowl and stir to combine. Season with salt and pepper to taste. Transfer the nut mixture into the prepared loaf pan. Cover with aluminium foil and bake in the oven at 190°C/375°F for approx. 60 – 70 min. Remove the aluminium foil approx. 15 min. before the end. Remove from the oven and let sit in the pan for approx. 10 min. before turning it out of the pan.
Meanwhile prepare the sauce. Peel and finely dice the remaining onion. Heat oil in a saucepan and fry diced onion for approx. 4 – 5 min. Add remaining tomato paste and flour and fry for approx. 3 – 4 min. until the mixture gets darker and slightly browned. Deglaze with vegetable stock and add red wine, soy sauce, bay leaves, and cloves. Bring to a boil, then reduce the heat to medium-low and let the sauce simmer for approx. 15 min. Season with salt and pepper to taste. Keep sauce warm until the nut roast is done and remove bay leaves and cloves before serving. Serve nut roast with sauce and mashed potatoes. Garnish with parsley. Enjoy!