Make the rice (optional, to serve). Add 1 cup of long-grain rice to a pot you (ideally) have a lid for. Pour in 1 1/2 cups of cold water and set over high heat. When you see the top of the water looking foamy and a little bubbly, pop the lid on (or use a plate/wooden board if you don't have a lid), lower the heat right down, and leave it for 12 minutes. After this time, remove the pot from the heat (keep the lid on) and set aside to finish steaming for another 10 minutes.
Mix the meatballs. Add the ground chicken, 2 chopped scallions, grated ginger, crushed garlic, 1/2 teaspoon of salt, 2 teaspoons of fish sauce, 1 teaspoon of sesame oil, 1/2 cup of panko breadcrumbs, 1 egg, and a good grind of black pepper to a mixing bowl. Mix well to combine.
Form the meatballs. If you're using the oven, heat it to 425°F (220°C fan) and line an oven tray with parchment paper. With slightly wet hands, scoop a heaped tablespoon of the meatball mixture into your hands and roll it into a ball. Place on the prepared tray, and continue with the rest of the mixture. If you're using your air fryer, you can place the meatballs directly into your air fryer basket.
Cook the meatballs. If you're using your oven, bake the meatballs for 20 minutes, or air fry them at 400°F (200°C) for 10 minutes, giving them a shake halfway through the cooking time, until golden.
Mix the sauce. Add 1 tablespoon of cornstarch to a bowl, then mix with 1/4 cup of water until smooth. Add 1/2 cup of pineapple juice, 1/4 cup of rice wine vinegar, 1/3 cup of honey, 1/4 cup of tomato ketchup, 2 tablespoons of soy sauce, and 1 teaspoon of fish sauce, and mix to combine. Set aside for now.
Make the stir-fry. Heat 1 tablespoon of oil in a large high-sided pan or skillet. Add the chopped bell peppers and scallions and cook, stirring, for about five minutes, until starting to soften. At this point, add the crushed garlic and toss through.
Add the sauce and meatballs. Give the sauce a mix (to make sure the cornstarch hasn't settled at the bottom of the bowl) and pour it into the pan. Stir until it's bubbling, thick and glossy, then add the meatballs and the pineapple. Toss everything through the sauce, then scatter with the sesame seeds, the green parts of the scallions, and cilantro. Serve while hot over the steamed rice if you like.