Missing ONE ingredient
Don'tcha just hate it when you're all set to make something or the mood suddenly strikes you and you realize you're missing one simple ingredient for which there is no substitution. :<(
It really depends on the dish but there is rarely things I don't make because I am missing one thing.
Unless it was flour and I was making bread I can usually make do.
Why not tell us the dish and what you are missing as a challenge?
Yes, I do hate that. And sometimes it is something that you really HAVE to have. Like ...
Shortbread cookies - but no butter in house
Beef Stew - but no onions in the house (or garlic)
Chili - but you're out of chili powder
This is why I love having a big freezer, but even so, it doesn't work for everything. I mean, I can be craving a spinach salad and that freezer isn't going to help me have spinach on hand (at least not spinach that I'd put in a salad).
Turmeric when I am making a curry.
Tarragon when I am cooking fish.
And for me, there are no substitutes for bacon and butter.