So, I’ve been thinking about an aspect of adventuring I’ve probably been a bit thin on…rations, supplies, hunger and so forth. I’ll probably add some other ideas later, but right now-
Could non-mages use rare ingredients? Not for spellcasting, but to use the bonuses they provide? What if a mage explains it to them first (maybe requiring a HARD roll)?
Yeah, a non-Mage could definitely benefit from using Rate Ingredients. I wouldn’t ask for a roll at all, just let it happen. That’s my take on it anyway. 
Well that really depends on how they are using the rare ingredient.
If they just need eat it, no roll.
If it requires a bit of prep that anyone could do with some knowledge roll for it.
If it is had make it a hard roll.
But if it would require very intricate magical ability of training to prepare then just say nope and they will need to find someone who can help them. Of course this could spin of to an adventure in itself potentially.