Combine all the ingredients for the black pepper sauce and stir until the sugar dissolves completely. Place it closer to your stove.
Placed the cubed tofu on a kitchen towel(paper towel), using different paper towel gently press down to get extra water out.
Heat 1 tablespoon of oil in a wok over medium high, add salt and freshly grated pepper and swirl it around the wok until fragrant.
Add the tofu to the oil and cook and toss until all sides turn golden brown. This should take around 5 to 6 minutes.
Transfer the tofu on a plate lined with paper towel.
Wipe the wok clean, heat remaining 1 tablespoon of oil on medium heat and add onions, garlic and bok choy.
Stir continuously until the bok choy began to wilt and onions are soften.
Add the black pepper sauce to the veggies and let them cook for a minute. Make sure to stir the sauce before adding, making sure any settled sugar get mixed in.
Just as the sauce starts to reduce, add the crispy tofu in the wok and give it a one quick toss. The all tofu cubes should be evenly coated.
Remove the wok from the heat, adjust salt and pepper as per your taste.
Garnish with toasted sesame and serve it warm.