Step 1 (Marinate Pork): Cut 400g pork tenderloin into 1/2-inch thick strips against the grain (critical for tenderness). Combine with 1/2 tsp salt, 1 tbsp Shaoxing wine, and 1 tsp cornstarch. Mix well and marinate at room temperature for 15 minutes.
Step 2 (Make Batter): While pork marinates, prepare batter. Whisk together 1/2 cup cornstarch, 1/4 cup flour, 1/2 tsp baking powder. Gradually add 1/2 cup ice-cold water while whisking until smooth (the cold water creates a crispier coating). Stir in 1 tbsp oil. Let batter rest 10 minutes.
Step 3 (Prep Sauce & Vegetables): Combine all sauce ingredients except cornstarch slurry in a bowl. Set aside. Have all cut vegetables ready (1-inch pepper squares, onion pieces).
Step 4 (Fry Pork): Heat 2 cups oil in wok to 170°C (340°F). Test by dropping a bit of batter; it should sizzle and float immediately. Dip each pork strip in batter, let excess drip, then carefully lower into oil. Fry in batches for 3-4 minutes until light golden. Remove and drain on rack. Increase oil temp to 190°C (375°F). Refry all pork in one batch for 60-90 seconds until deep golden brown and extra crispy (double-frying is key for crunch that lasts).
Step 5 (Stir-fry Sauce): Remove all but 1 tbsp oil from wok. Heat over medium. Add sauce mixture and bring to simmer. Stir in cornstarch slurry and cook for 1-2 minutes until thickened to a glossy, syrupy consistency that coats the back of a spoon.
Step 6 (Combine): Add vegetables and pineapple to sauce. Stir-fry for 2-3 minutes until peppers are tender-crisp. Add fried pork. Toss quickly for 30-45 seconds just to coat (do not overcook or coating will soften).
Step 7 (Serve & Store): Serve immediately over steamed rice. Garnish with sesame seeds. For best texture, consume immediately. Leftovers will become soggy; store in refrigerator for 1 day and reheat in oven at 180°C (350°F) for 10 minutes to crisp.

