I found the same thing in our local takeouts up in Rockland Co. This might be a good question for the General board. I bet it's rampant. I keep Coleman’s dry mustard on hand. Take a tsp; add a bit of water stir.
Our trick to lighter, homemade ice cream: 2% Greek yogurt. It’s a refrigerator staple, and it “churns” into a rich, creamy confection when blended with a little honey and vanilla bean. Bonus: You don’t even need an ice-cream machine.