Prepare a yeast dough from light butter, flour, salt, beer and yeast and let it rise. Divide into equal-sized pieces. Spread each dough ball on the palm of your hand, place a tomato half, a piece of knockwurst and grated cheese on top. Twist the dough balls together, place on a greased baking sheet, brush with beaten egg and bake over medium heat until golden brown.
Beer doughnuts can also be fried in boiling fat.