Temperature (think Goldilocks and the Three Bears)
Just Right
When my son was really small say around one or two years old, I used to have quite the repertoire of meals that allowed for a swirl of something cold to be added after heating to cool it down to a tolerable temperature. I just thought that was a thing that children required. He was out first child. In particular, I can remember meals that I added yoghurt to (kind of Moroccan or Spanish dishes).
Patience
Waiting to something to be the right temperature takes patience.
This has been a learned behaviour over some time. The timer on his device he uses for audiobooks is a great thing for determination of waiting times. Especially when baking has just emerged from the oven!