I make a vegan buttercream icing with Crisco, powdered sugar, vanilla extract, and soy milk/nut milk/water. If I skip the soy milk/nut milk and use water for the liquid, is the icing totally shelf stable, considering that all of the individual ingredients are shelf stable for months-years?
[EDIT] Ok, it is not shelf stable. How can I find out how long it can be left out at room temperature? I have seen people online saying anywhere from 2 days to 2 weeks.