Peel, wash and halve the potatoes and cook in boiling salted water for about 20 minutes. Onions peel, halve and cut into fine strips. 1
Add the tomato paste and sauté briefly. Deglaze with beer and broth and simmer for about 15 minutes on a mild heat.
In the meantime heat milk and butter in a pot. Drain the potatoes, add milk and butter, mash with a potato masher to form a puree, season with salt, pepper and nutmeg. Keep warm. Heat 2 tablespoons of oil in a frying pan.
Fry the bratwursts for about 10 minutes, turning them until golden brown.
Wash the chives, shake dry and cut into fine rolls. Season to taste with soy sauce, salt and pepper. If necessary, stir the starch with a little water until smooth, thicken the sauce with it. Arrange sausages and puree on plates.
Pour sauce over the sausages and sprinkle with chives.