Mold hates a dry bento box.

The most effective deep-clean is a hot soapy soak, a crevice brush, and then letting the whole thing air-dry completely before you put it away.

The scrubbing only gets you halfway. Mold isn’t killed by soap—it’s prevented by removing all moisture. So take the box apart as much as you can: pop out the divider, the silicone gasket, the lid seal. Soak everything in warm water with dish soap for ten minutes. Then go at the edges with a bottle brush, a toothbrush, or one of those little silicone brush sets. For stubborn pink or black spots, a paste of baking soda and water works well.

Rinse everything thoroughly, then resist the urge to towel dry. Towels leave film and moisture in the corners. Set the pieces on a dish rack upside down, making sure the divider edges are facing down so water can drain out. Give it a few hours. If it’s in a hurry, you can use a clean dish towel and a fan, but nothing beats letting gravity do the work.

A clean bento box is a dry bento box.