I have a salad dressing recipe that calls for food starch, but I have no idea what that is. I tried making the recipe without it, but it was way too thin.
It is unusual that your recipe calls for food starch. This is a term usually used by food manufacturers to indicate a starch added to a food that is generally used as a thickening agent. The starch can be made from wheat, potato, rice, corn or tapioca.
Such starches do require heating to activate their ability to thicken sauces and dressings. A good choice might be for you to use corn starch in your recipe. It does form clumps when added directly to warm or hot liquid, so start by adding it to cold water to dissolve. Then add it to the sauce as it heats. If the sauce boils, the cornstarch will lose its thickening properties.
Thanks for writing,
Timothy S. Harlan, M.D.