Soak it, don't just rewash it

The reason your lunch box still smells after washing is that the odor is baked into the plastic, not sitting on the surface.

Soap and water only remove the visible film. Grease and food oils penetrate plastic, then go rancid. That’s the smell you’re getting.

So stop rewashing. Soak instead. Fill the box with hot water and a cup of white vinegar, let it sit for an hour, then wash normally. For really stubborn cases, make a paste of baking soda and water, coat the inside, let it sit overnight, then rinse.

Your secret weapon is sunlight. Set the clean, dry lunch box in direct sun for a few hours. UV light breaks down the odor-causing compounds and kills bacteria. It sounds like woo, but it genuinely works on plastic food containers.

If you’ve soaked, baked, and sunned it and the smell is still there, that plastic is done. Retire it — your food will taste like your lunch box.