Preheat oven to 200°C. Line a baking sheet with foil, place a greased wire rack on top.
Pat wings dry, season with salt and pepper. Arrange on rack and bake for 40–45 minutes, flipping halfway.
Simmer pineapple juice, brown sugar, soy sauce, ketchup, vinegar, garlic, ginger, and chili flakes in a saucepan.
Mix cornstarch with 15 ml water and stir into the glaze. Simmer until thick and glossy, about 5 minutes.
Toss hot wings in a bowl with the warm glaze until fully coated.
Return wings to the rack and bake for 10 more minutes to set the glaze.
Transfer to a platter, sprinkle with green onions and sesame seeds. Serve hot.