If you are in the middle of fighting a very hard boss and all your healing options have been exhausted, why can't you eat a piece of food to help you regain some health?
That's what healing potions are for. DnD uses limited resources for a reason - and as Larian removed healing through food, then combat encounters should be balanced appropriately, aka. not requiring unending supply of healing items. Personally, I can't say I run into the issue when I was short on healing spells/items in combat, but I do think an original 5e short rest system would be probably better then was Larian currently has - while playing Solasta classes that tended to take the most beating could also effectively recover during short rests.
