The cook tells you that he needs a newt's eye, a Greenman's ale, a rotten tomato, and a dirty blast. When asked how to make a dirty blast, he tells you to add ashes to a fruit blast that you make yourself. The fruit blast given by Curator Haig Halen for completing the The Dig Site quest will also work. The Cook also gives you 100 coins to buy everything and allows you to keep the change. Once you have all four items, give them to the Cook.