Heat oil in a deep frying pan over medium-high heat. Add ginger and garlic, and stir-fry until fragrant and tender (20-30 seconds). Add Shaoxing, soy and oyster sauce, bring to a simmer, then add pepper and tofu, and simmer, without stirring, until tofu is warmed through (5 minutes). Add cornflour mixture to pan and stir gently to combine and thicken sauce, being careful not to break up tofu. Serve with steamed greens and rice.