Add stock and bring to the boil. Stir in tomato paste. Season with salt, coloured pepper and paprika and cook for another 5 minutes. Peel, wash and roughly grate the potatoes. Peel onion and grate finely.
Mix potatoes with onion and egg yolk. Season with salt and pepper. Heat oil in a frying pan. Add four portions of toasted dough, press flat and fry until golden on both sides. Arrange on a plate with the vegetables.
Sprinkle with thyme leaves and garnish with a bouquet.