Currently my portable emergency food for random attacks of the munchies is an "Eat Natural" puffed rice and fruit bar (this is much like any muesli or grain meal-bar but rice-based and hence gluten-free); my static emergency food kept at work in case I can't conveniently buy lunch one day is a stock of Trufree "just add boiling water and wait five minutes" mashed-potato-and-veg snack pots. Both of these are perfectly acceptable food; the snack pot takes a bit of care in preparation to ensure you don't end up with nasty dry bits at the bottom, but is entirely edible once you've managed that.