stews that need more food than others?

I made a stew with fresh water, two yellow herbs and an orange herb, plus food from the bin. They said the stew was yummy.

Then I made the soapy stew with salt water and three white herbs to get the soap.

Then I tried to make a stew with fresh water, an orange, yellow and white herb plus food. It keeps telling me the stew is cooking, but it's just "cold and uncooked" when the heat from the rocks wears off.