In a large skillet, heat the canola oil until nearly smoking. Add the pork and stir-fry over high heat until lightly charred in spots, about 5 minutes. Add the ginger and garlic and cook until fragrant, about 30 seconds. Add the leeks and stir-fry until tender and lightly browned in spots, 5 to 6 minutes. Stir the sauce, add it to the pan and cook, scraping up any bits stuck to the bottom, until thickened, about 1 minute longer. Serve right away with rice.