Virtual Villagers-Lost Children-The Stew?

I have tried to make my stew 3 times now. It keeps turning up "nasty-not edible" How do I make my stew so that I can get a villager to go to bottom of pond to get last gong piece. I added water, 2 orange plants, 1 black plant and food. Everytime it is nasty! Can someone tell me how to make my stew so that villager has underwater breathing. You can also tell me how to make the other stews. I saw on a cheat sheet that you could make several stews. I just do not understand how to do it!