Dried-out, rock-hard brown sugar happens to the best of us, and we're all familiar with the classic tricks recommended to get it soft again—stick a slice of bread or an apple wedge in the bag, and osmosis will kick in overnight. But seriously, in what universe is that practical? I want cookies now!
Besides, why waste food when you can return a brick of brown sugar to its former glory in less than a minute? It's an easy trick I perfected in my restaurant days, when harried line cooks would occasionally raid the brown sugar bin and leave the lid less than secure in their rush.
All you need is one-eighth of an ounce (i.e., three-fourths of a teaspoon, or 3.5 grams) of water for every eight ounces of dried-out brown sugar. (Just one more reason everyone should own a digital kitchen scale; without one, the best you can do is guess.)
Combine the sugar and water in a zip-top bag, press out the air, seal, and zap for 15 seconds in the microwave. A portion of the sugar will look completely melted, and that's just perfect. Working through the bag, press on that melty spot with your fingers to start breaking up the lumps, then knead the brown sugar until it's homogeneous. It's a strangely soothing process, squishing the warm sugar around the bag, which will help reduce the stress you probably felt upon discovering that your brown sugar was hard as a rock.
No microwave? No problem. Just seal the bag and let the water stand with the sugar for about 30 minutes before you get to work.
By kneading water directly into the sugar, you're instantly replacing (and distributing) what was lost, a vastly more precise and effective route to rehydrating brown sugar than indirect methods such as sliced fruit, bread, or even a damp paper towel placed over the sugar in a bowl. Plus, no food waste or dirty dishes. The brown sugar can be stored directly in the zip-top bag.
So save your apple slices and bread for a cheese plate, and never let dried-out brown sugar slow you down again.