In a small bowl, whisk the stock with the soy sauce, cooking wine, ketchup, sugar, chile-garlic paste, vinegar and 1 teaspoon of the cornstarch. In another medium bowl, season the pork with salt and toss with the remaining 1 teaspoon of cornstarch.
In a large nonstick skillet, heat 2 tablespoons of the peanut oil until shimmering. Add the pork in a single layer and fry over high heat, undisturbed, until nearly cooked but still pink in the center, about 1 1/2 minutes. Add the ginger and garlic and cook, stirring, just until fragrant, about 1 minute. Transfer the pork to a plate.
Add the remaining 2 tablespoons of peanut oil to the skillet and heat until just smoking. Add the mushrooms and scallions, season with salt and cook over high heat, stirring occasionally, until lightly browned, about 5 minutes. Return the pork and any accumulated juices to the skillet and toss with the mushrooms and scallions. Stir the sauce, add it to the skillet and bring to a boil. Cook until thickened, about 30 seconds. Serve at once.
Serve With: Steamed rice.