Wednesday night: half a cabbage, three eggs, the end of a jar of something. Dinner gets made anyway, and every so often it is the best thing anyone ate all week.
That is the entire mechanism. Creativity is rarely conjuring from nothing. It's what gets done with an awkward set of available parts, under a real constraint, without waiting to feel ready.
The sensation of being inspired usually turns up about ten minutes after starting rather than before. Which makes it less a prerequisite than a reward, and it tends to arrive for whoever opened the fridge.