To the person who found my blog by Googling "currywurst recipe" (sadly, I am only ranked fifth), I have a piece of advice.
The four Google results before my blog all reference knackwurst as an ingredient for currywurst. This is the Berlin way to make a currywurst, and it is abominable. Proper currywurst, regardless of what Berliners may claim, is made with bratwurst.
There are two different variants of currywurst to be had in Germany. One is the Berliner kind made with knackwurst, which is only eaten in Berlin and surrounding areas. The other is the Ruhrgebiet kind made with bratwurst, which is eaten everywhere else in Germany. One is an abomination of which none speak save in hushed whispers. The other is the only true and proper currywurst.