Inform has no built-in way of doing this, so you’ll have to create your own. If you move the stew off-stage when it’s eaten (and it is never off-stage otherwise), you could check for that, or you could make eating the stew set a flag, something like this (untested):
[code]Stew-eaten is a truth state that varies.
Carry out Bob eating the mushroom stew:
now stew-eaten is true.