For the basic sauce, heat the ketchup in a saucepan (caution, splash!) And season with plenty of curry powder, paprika powder and Worcester sauce to taste.
Peel the onions, cut into very fine cubes and season with plenty of chili powder, paprika powder and Tabasco in a bowl. Then add the vinegar and stir well.
Now cut into the sausage five to six times on each side and fry in hot fat in the pan. Make the side with the cuts very crispy. When the sausage is crispy on one side and slightly dark on the other, remove it from the pan and cut the sausage on the plate into pieces about the thickness of a finger. Then season generously with curry powder and paprika powder (if you like, you can also use chili powder) and round off with the sauce.
Finally, mix 3 - 4 tablespoons of the sauce with the onions and serve to measure yourself.
Warning: Under no circumstances should you try the onions without the sauce - it can be a nasty sight.
French fries ideally go with it and it tastes like in Berlin.