Your sandwich needs a moisture barrier

The trick to a non-soggy sandwich is stopping wet ingredients from touching the bread in the first place.

The usual suspects are tomatoes, pickles, and condiments. They’re basically water balloons that pop over four hours. The fix is to put something between them and the bread — a slice of cheese, a piece of lettuce, or even a smear of mayo or butter. Fat repels water, so a condiment layer does double duty.

The 100% guarantee move is to pack the wet stuff separately and assemble at lunchtime. Dressing in a tiny container, tomato slice in a baggie. Takes 10 seconds and the sandwich tastes better because the bread isn’t damp and cold.

If you can’t do separate packing, two extra tricks: blot the tomato slices with a paper towel, and toast the bread lightly. Both remove or resist moisture. And drop a paper towel in the lunchbox near the sandwich — it absorbs ambient moisture like a sponge.

Trusting a tomato to behave for four hours is optimism. Build a barrier instead.