The trick is drying, not scrubbing

The trick to keeping mold out of lunch box crevices is drying it completely before you close the lid. Scrubbing gets the gunk, but mold grows because of trapped moisture, not leftovers.

Wash it with hot soapy water like normal, then pop out the rubber seal and anything else removable. That seal is where mold always wins — food juice gets under it, and a regular rinse won’t touch it. Wipe the seal channel with a cloth or a toothbrush if it’s crusty. If you already see black spots, a vinegar soak (half water, half vinegar) will kill the spores.

Then dry it. Every part. Leave the lid open or the latches unclipped so air can move. Do that and it’s basically impossible for mold to set up shop.

That’s it — the drying is the whole game.