Briefly dip the sausages in boiling water, fry them in butter until golden brown on both sides. Take the sausages out of the pan, extinguish the frying fat with the beer, thicken the broth with cold-mixed cornstarch, season with salt, sugar and lemon juice. Let sausages soak in the sauce for 5 to 7 minutes. This goes well with mashed potatoes and red cabbage.