This article is from the Food Preserving FAQ, by Eric Decker email@example.com with numerous contributions by others.
My tofu book says to dry it: It is preferred if you make your own tofu,
make it as firm as you can. Freeze it for a day or 2, take it out and let
it thaw out. Squeeze as much water as you can out of it. If you want
crumbled or mashed, do that now, or slice it or cube it. Anyway now after
it is in the form you need it, put it in the oven at 175 degrees for up to
6 hours. Do not let it get brown but make certain it is a golden tan
color. Store after drying on the shelf in a sealed plastic bag. To
reconstitute it, mix cup for cup with hot water, stock, or whey. Stir and
let stand 15 minutes or so or until the previous spongy consistency
returns. Drain off any liquid not absorbed. You can also reconstitute it
in a marinade, full strength or diluted with water. You can also add dried
tofu to soups, meat loaf or moist vegetable patty mixtures etc.