In A Small Saucepan, Combine Mustard And Vinegar; Let Stand For 30 Minutes. Whisk In The Sugar And Egg Yolk Until Smooth. Cook Over Medium Heat, Whisking Constantly, Until Mixture Just Begins To Simmer And Is Thickened, About 7 Minutes. Remove From The Heat; Whisk In Honey. Chill. Serve With Pretzels. Store In The Refrigerator.