Prepare the Chicken: In a medium bowl, toss the chicken cubes with 2 tbsp of cornflour, salt, and pepper until each piece is lightly coated. This thin coating helps the chicken brown beautifully and slightly thickens the sauce later.

Cook the Chicken: Heat 1 tbsp of vegetable oil in a large frying pan or wok over medium-high heat. Add the chicken in a single layer, being careful not to overcrowd the pan (cook in two batches if necessary). Cook for 5-7 minutes, turning occasionally, until the chicken is golden brown and cooked through. Remove the chicken from the pan and set it aside on a plate.

Sauté the Aromatics and Vegetables: Add the remaining 1 tbsp of oil to the same pan. Add the chopped onion and bell peppers and cook for 4-5 minutes, until they begin to soften but still have a bit of a crunch. Add the minced garlic and grated ginger and cook for another minute until fragrant. I find that stirring constantly at this stage prevents the garlic from burning.

Create the Sauce: In a small bowl or jug, whisk together the pineapple juice, soy sauce, rice vinegar, and brown sugar. Pour this mixture into the pan with the vegetables. Bring it to a gentle simmer.

Thicken the Sauce: Once the sauce is simmering, give your cornflour slurry (1 tbsp cornflour mixed with 2 tbsp cold water) a quick re-stir and pour it into the pan. Continue to stir as the sauce bubbles and thickens, which should only take about 1-2 minutes. You're looking for a consistency that coats the back of a spoon.

Combine Everything: Return the cooked chicken to the pan along with the pineapple chunks. Stir everything together gently to coat the chicken and pineapple in that glossy sauce. Let it all heat through for another 2 minutes.

Serve Immediately: Take the pan off the heat. Garnish with sliced spring onions and toasted sesame seeds if you like. Serve hot with fluffy basmati rice or noodles.