How can I prevent reductions from turning into molasses?

Question

Last night I attempted to make a reduced sauce out of equal parts soy sauce, mirin, sake, and sugar. I let it simmer in a saucepan over medium-low heat until it got to a mildly viscous consistency where dragging my spatula briefly left a trail in the pan, then put it in a jar and put it in the fridge. The next day it was practically solid - I heated it up for 30 seconds in the microwave and it had the consistency of molasses. This was despite it being still pretty runny when I took it off the heat.

I've noticed this has happened a couple of times, and I want to know if there's something I'm doing wrong. Perhaps I should be taking it off the heat much earlier (though at that point there would be no trail left in the pan by my spatula, contradicting what most people suggest).

I also noticed at one point the mixture was bubbling quite a bit - I think I let it get too hot, which promoted crystallization of the sugar. Is it possible overheating the sugar results in too thick a reduction, and one should vigilantly watch their saucepan to prevent it from overheating?

Answer 1

You already stumbled over the correct answer - your reduction was held too long on the stove.

It doesn't matter what liquids and aromatics you are including, at the end you are making a sugar syrup. If you get it to be the preferred viscosity when it is in the pan, it will be too thick when it cools down. And yes, you do have to be very vigilant when working with sugar syrups of any kind, your timing has to be right up to maybe 20 seconds.

If you want your sauce to be thinner than what you are getting right now, you should either cook it for shorter time, or add more liquid after it has cooled. Both will work, you can choose depending on which is more comfortable for you and which flavor profile you prefer.

Most recipes of this kind are also meant for immediate serving. If you are keeping leftovers, you might take it to a higher viscosity, eat it hot, and then again stir in more liquid before putting it in the fridge.

And if the spatula sign is not useful for you, don't use it, it is just suggested as a help for the cook. It is maybe not well suited to the exact recipe, or maybe you imagine it differently.