How to Press Tofu
Tofu is versatile, inexpensive, and nutritious, but if you're unfamiliar with it, it can also be a little overwhelming. It comes in all kinds of varieties (Smoked! Flavored!), and textures. At most American supermarkets, you'll find blocks of tofu listed by their softness: silken, soft, firm, or extra firm. The softness of the tofu correlates to the moisture content in it. Tofu is, after all, coagulated soy milk—the more moisture it has, the softer it will be. When you're talking about pressing tofu, it refers to the last two texture categories of tofu; if you attempt to press silken or soft tofu, it'll just fall apart.
Why press tofu in the first place? If you want to get tofu crispy and seared on the edges, you need to get as much moisture out of it as possible. Basically, in any recipe where tofu is cut into slices or cubes, pressing will help with the overall result. That means starting with firm or extra firm tofu, but you can also get a little extra insurance. Freezing and then defrosting tofu is a good way to do this, but it takes time. If you want crispy tofu quickly, the best method is pressing it.
If you eat tofu frequently, it might be worth it to invest in a tofu press. But even if you don't have one, you can still press tofu pretty easily. All you need is a clean dish towel or a few paper towels and a heavy object, like a cast-iron skillet, big cookbook, or can of tomatoes. Take the tofu block out of its packaging, drain it, and wrap it in a clean dish towel or a couple layers of paper towels. Then put the wrapped block on a plate, put another plate or a cutting board on top of the block of tofu, and add the heavy object to the top of the stack. You want something that's heavy enough to squeeze water out of the block, but not so heavy that it's going to crush it—no 50-pound weights or anvils, if you have those lying around. Then you just let that sit for about half an hour. The tofu should expel some water, enough to soak the towel, and be more compact. Great! Now you can use it in whatever dish you're cooking, from Shaking Tofu to Crispy Tofu Bibimbap.