Put the lunch box in the sun

Leave the smelly plastic lunch box in direct sunlight for a few hours and the fish or curry smell will mostly disappear.

The reason scrubbing doesn’t work is that curry and fish oils work their way into tiny pores in the plastic. Soap and hot water can’t get them out. Ultraviolet light breaks those odor molecules down, which is exactly what you want.

Wash the box normally, dry it, then put it outside in the sun with the lid open. One afternoon usually does it. If it’s cloudy or you don’t have outdoor space, crumple newspaper inside, seal the box shut, and leave it overnight. The paper absorbs the odor. A paste of baking soda works too, but it’s messier and takes just as long.

One thing not to do: don’t microwave the plastic or run it through hot dishwasher cycles to kill the smell. Heat just bakes it in deeper.

If it still stinks after a couple of sun sessions, that container has lived its life. Toss it and get glass next time.