Boil washed potatoes in a pan of lightly salted water. Cover and simmer for 20-25 minutes until tender.
Drain well, peel off the skin then mash the potatoes while hot until you get a smooth mash. Beat in butter and enough milk to obtain a soft consistency. Season with salt and pepper to taste. Put in an icing bag and pipe out desired patterns and serve with sauce.
Place chicken stock in a saucepan together with celery, big onion and mixed herbs. Bring to a boil and simmer for 15 minutes. Strain the stock.
Heat butter and cook the flour over very low heat, stirring constantly until it comes away from the sides of the saucepan. Gradually add in the stock stirring until smooth.
Stir in the tomato puree and dark soya sauce and bring to a boil.
Simmer for about 50 minutes to thicken the sauce to the desired consistency. Season to taste and serve with the piped mashed potatoes.