This is a favorite cooking tool that I store next to my stove. It’s a wonderfully simple and useful tool modeled after a tombo, or dragonfly stick I use in throwing (pottery speak here- made on a potters wheel) consistantly sized cups. However, this cooking version is a tombo with its wings torn off… Sorry tombo!
My reduction tester is just a chopstick with a rubberband around it. When I’m cooking, and the recipe says to cook a liquid until it is reduced by half or a third, etc… I take out my reduction tester and dip it into the liquid and shift the rubberband up till it just marks the level of the liquid in the saucepan. Now it marks my beginning liquid level.
To measure my progress in reducing a liquid, I dip the chopstick back into the liquid and see how the new level compares to the original level marked with the rubberband. This lets me quickly and more importantly, accurately gauge how far along in my reduction I am.
To make your own reduction tester- look for really small rubberbands, as they fit around the small diameter of a chopstick without slipping around and losing your level. The green one pictured on my reduction tester can be found in a farm supply store. It’s a perfect size- that of a cherrio. It’s manufactured for use in castrating animals… but I bet you didn’t need to know that either…