I haven't had it before, but it looks like it started in Detroit and is a steak sauce. In an article I just read about it "The history of Zip Sauce starts with Mario Lelli, who owned and operated a high-end Italian restaurant along Woodward Avenue that opened in 1939. As the story goes, Lelli’s restaurant was a hot spot where northern Italian recipes reigned supreme. But what made it a household name was its steaks and famous Zip Sauce. People came from far and wide to eat at Lelli’s and savor the Zip Sauce. Its popularity grew to the point where other restaurants started making their own version". The most common recipe seems to be:
1 teaspoon crushed dried rosemary
1⁄4 teaspoon dried leaf thyme, rubbed between fingers til fine
1⁄4 teaspoon garlic powder
1 teaspoon dry parsley flakes
1⁄4 lb butter, melted
1 teaspoon salt
1 tablespoon Dijon mustard
1⁄2 teaspoon coarse black pepper
1 1⁄2 tablespoons Worcestershire sauce
1⁄4 teaspoon ground cumin
1⁄8 teaspoon cayenne pepper
1⁄8 teaspoon white pepper
Sounds like it might be a good sauce. Thanks for letting us know it existed Kristin.