Seelachsbrötchen ― WTF IS IT??!

...a bread roll filled with 3-5 pieces of chopped raw onions and salted (redder than red) pollack fish. Beware: This thing really is %&$#ing SALTY! So if you're not prepared with water or some kind of beverage to chase it down, don't even attempt to eat it. I recently saw and tried this badboy for the first time at the Hamburg Fish Market. For €2,50 a pop, I shoulda opted for the Matjes Brötchen instead :/