The lettuce trick fixes most bento sogginess.

Packing a bento box with wet and dry foods without sogginess comes down to one thing: walls.

The moisture problem isn’t time — it’s contact. Saucy food doesn’t spawn moisture out of nowhere. It touches dry food, and the dry food soaks it up. So the fix is physical separation. The easiest and cheapest barrier is a big lettuce or cabbage leaf. Line the dry side of the box with it, and it catches the moisture. It’s edible, it’s crisp, and it keeps rice from turning into a paste.

The rest is placement. Put wet foods at the bottom or in a corner so they can’t run downhill onto crackers or fried things. Dense rice can handle being near moist food way better than chips can. And anything dressed — salad, pasta, slaw — gets dressed in its own container, or you accept that it will be a little soggy by design.

Silicone cups, paper baking cups, and tiny sauce containers do the rest. One dollop of sauce in a cup beats sauce poured over food every single time. If you have a bento with built-in dividers, great. If not, the cups are doing the same job.

Walls are cheap. Soggy lunch is sad.