Buy the vented Sistema. It does what you're asking.

Vented lunch boxes are real — Sistema makes a whole fruit-and-veg line with vented lids, and that’s what you want.

Here’s the thing: produce doesn’t go soggy because it’s in a box. It goes soggy because the box seals in moisture and condensation drips back onto the lettuce. Vents fix that by letting water vapor escape. Sistema’s Fruit & Veg and Bento ranges have little vent sliders on the lids for exactly this purpose. They’re cheap and easy to find.

The other 50% is prep. Dry the leaves before you pack them. Throw in a folded paper towel to soak up stray moisture. And keep wet stuff — grapes, tomato halves — in a separate compartment so it’s not sharing airspace with your crackers or salad. Most Sistema bento boxes have dividers, which handles this.

If you want the gold standard for crisping, Rubbermaid FreshWorks is great, but it’s bulky — better for a fridge than a lunch bag. For lunch, a vented Sistema with a paper towel beats everything else I’ve tried.

No container can save produce that went in wet. Dry it first, and the vents do the rest.