Sabrett

A Sabrett push cart hot dog isn't complete until it's slathered with the tangy orange/red onion sauce. For a buck or two you can grab a hot dog with the works on the fly from these popular umbrella-covered food carts in many major cities and at special events. You see hundreds of 'em in New York City, especially around Central Park. In fact, that's where the sample for this re-creation was obtained. While most of the Sabrett toppings are standard hot dog fare—ketchup, mustard, sauerkraut—the onion sauce makes these hot dogs special. 

Source: Even More Top Secret Recipes by Todd Wilbur.