Soak first, then brush the corners

The easiest way to handle a compartment lunch box is to soak it in hot soapy water for ten minutes, then hit the small corners with a brush.

That soak is what actually does the heavy lifting. It loosens the dried hummus, peanut butter, or whatever leaked into the seams. Without it, you’re just smearing stuff around with a sponge. After ten minutes, the flat compartments wipe clean in seconds.

The corners are a different beast. Use a bottle brush or an old toothbrush — something with bristles that can actually reach in. A regular sponge is useless there. And if your lunch box is dishwasher safe, the dishwasher will handle 90% of it, but check the corners after; sometimes residue stays in the crevices even after a cycle.

Then dry it fully. Leave it open or upside down on a rack. This is the step everyone skips, and it’s why lunch boxes start smelling like sour milk after a few weeks. Moisture trapped in corners is the enemy.

Don’t overthink it: soak, scrub with a small brush, dry completely. That’s the whole trick.