Heat the cooking oil. Add the tofu, garlic, onion, ginger and pepper. Stir fry for half a minute.
Pour in about a tablespoonful of soy sauce. Add the sugar. Stir fry until the tofu soaks up the liquid.
Add the pechay.
Add a little more soy sauce. Pour in the Sriracha. Continue stir frying just until the leaves are wilted.
Drizzle in a few drops of sesame seed oil. Stir. Serve hot.