Yes — just make peace with silicone

You can get an all-stainless bento box that’s dishwasher-safe, but almost every one of them has a silicone gasket somewhere. Good news: that’s not plastic, and it’s dishwasher-safe too.

The reason is simple: metal lids don’t seal. To keep soup or dressing from leaking into your bag, manufacturers need something squishy in the lid — and they use food-grade silicone, not plastic. So you get an all-steel body, an all-steel lid, and one invisible silicone ring that makes it actually work.

If you’re hardcore “no plastic” and want zero silicone as well, your options shrink to one-piece steel containers with a snap-on or friction-fit lid. Those exist — LunchBots’ original line is a good example — but they are not leak-proof. That trade-off is fine for dry food, awful for yogurt.

Dishwasher-safe? Yes. I’ve run steel bento boxes with silicone seals through the top rack many times with no problems. Some manufacturers say hand-wash to keep the seal from fading, but that’s caution, not a real restriction.

Bottom line: if you can live with a silicone seal, you get your all-stainless box. If you can’t, get the non-leak-proof version and keep it to sandwiches.