Drain all the water from the pack of extra-firm tofu and place it on a flat surface. Then place the block of tofu on top. I like to place a double layer of clean kitchen towel over the surface before placing the tofu.Place a heavy object on top of the tofu, like a cast iron skillet or can of beans. It should be pressed evenly. You can also use a tofu press if you have one. Let it sit for 20 to 30 minutes. It is important to press the tofu to drain the excess water from it so do not skip this step. I replace the paper towels once it between while the tofu is draining. Once pressed, cut the tofu into 1-inch cubes.