A New York hot dog features an all-beef hot dog in a white bun with onion relish, sauerkraut, and deli-style brown mustard. Its uniqueness lies in the "dirty water" method it uses.
Vinegar, red pepper flakes, cumin, onion powder, garlic powder, and other seasonings are combined in boiling water. As the all-beef dog boils up, it takes on all of those spices.
A part of what makes the New York street-cart-style hot dog especially authentic is the sweet and sour onion relish, which pairs beautifully with the sauerkraut and mustard.
The original onion sauce is from the iconic Sabrett hot dogs, which is where most stands in New York get their meat. The exact recipe that Sabrett uses has long been a secret.