Step 1Rinse the tofu in cold water. Cut the cube of tofu in half, then into half-inch slices. Set aside on some paper towels or in a wire-mesh colander to drain.
Step 2To prepare the seasoning, combine soy sauce, garlic, green onions and the optional red pepper or chili powder. Set aside.
Step 3In a large skillet, heat the vegetable oil. Place the tofu carefully into the skillet, making sure each rectangle is flat on the bottom of the skillet. (Be careful because the water in the tofu will make a splash. Cover with a wire-mesh splashguard, if you wish.) Cook on medium to high heat until the tofu is lightly browned on both sides (about 4 to 5 minutes). Be careful not to overcook or the tofu will lose its moisture and texture.
Step 4Lower the heat and spoon the soy mixture over each tofu slice. Cover and cook for 2 to 3 more minutes until the tofu is slightly steamed and infused with the seasoning.