Cut the beef and tofu into bite-sized pieces.
Sprinkle a little salt on the tofu and let it sit for 10 minutes.
Heat cooking oil in a pan and fry the tofu on both sides until golden brown.
Remove the tofu and stir-fry the beef in the same pan.
Make the sauce by mixing soy sauce, sugar, minced garlic, pepper powder, and water.
Add the tofu and beef to the pan, pour the sauce over, and simmer over medium-low heat.
When the sauce has reduced, add green onion and simmer once more.
Transfer the finished braised beef and tofu to a plate.