Why can't my Sim make Ambrosia?

I'm almost positive your sim doesn't need perfect quality lifefruit or deathfish. The sims 3 wiki says ambrosia can be prepared any time of the day, but I haven't made it in a while and don't remember. But as Karritz says, it's only a single serving unless you have a mod (I think from MTS) that makes it also a multiple serving dish.

Don't leave it out. Sims will autonomously eat it. I've had that problem (of the wrong sim getting to the ambrosia) before.