Are you running out of adhesive? You’re not alone. I made this list of items that contain adhesive, one of them being a recipe for Food Starch as mentioned by Redditor/u/jredwards. I also have a walkthrough and a .gif at the bottom of how to find all the ingredients for Food Starch below. See you out in the Wasteland!
Fallout 4 Vault Dweller’s Survival Guide (Collectors ed., Vol. 1). (2077). Boston, MA: Vault-Tec Documentation Department.
Find more here.
The easiest way to get the Vegetable Starch ingredients is to go to Gray Garden, which is found at the picture below. It is South West of Lexington.