I think what Charley means is that there are 18 types of stew, and that each type of stew may have more than one recipe.

For example, you can make "feels healthier" stew with the recipes: WWW, BBR, or POO. Whichever one you make first gives you credit for the "feels healthier" stew. If you make POO (giggle) you will get 1/18 credit. If you then make WWW or BBR you get nothing. You stay at 1/18.

Here is more on stews, but the link is a [spoiler].

-Borg

PS To read the stew recipes above you need to highlight them (they are written in the same color as the background).