How to Make It
In a small bowl, whisk the cornstarch with 1 1/4 cups of water. In a large skillet, heat the oil. Add the pork, peppercorns and a generous pinch of salt and cook over high heat, stirring and breaking up the meat, until crumbly and lightly browned, about 3 minutes. Stir in the chile-bean, hoisin and soy sauces and cook, stirring, until fragrant, about 2 minutes. Stir in the cornstarch slurry and simmer until thickened, about 2 minutes. Stir in the 1/4 cup of sliced scallions and season with salt. Keep warm over very low heat.
Meanwhile, set a steamer basket in a large saucepan. Add 1 inch of water and bring to a boil. Add the bok choy to the basket, cover and steam until crisp-tender, 4 to 6 minutes. Transfer to plates or a platter.
Spoon the pork over the bok choy, garnish with sliced scallions and serve right away.