Peel and chop the onion and garlic finely. Core the red pepper and cut into small cubes. Peel the pineapple, remove the stalk, and cut into bite-sized pieces.
Heat 1 tablespoon butter in a pan over medium heat. Add the pineapple pieces and sprinkle with freshly ground pepper. Fry for 2 minutes until lightly caramelized. Set aside to cool for 5 minutes.
Cut the chicken breast fillets into bite-sized pieces. Heat 3 tablespoons olive oil in the pan over medium-high heat. Fry the chicken for 2-3 minutes until lightly golden, then remove and set aside.
In the same pan, fry the onion and garlic for 1-2 minutes until softened. Add the diced red pepper and cook for 1 minute. Stir in 2 teaspoons curry powder for 30 seconds, then sprinkle 1 teaspoon flour over the mixture and stir well.
Pour in 150 ml poultry stock and the coconut milk. Bring to a simmer over medium heat and cook for 5 minutes. Return the chicken to the pan and cook for 5-7 minutes, stirring occasionally, until the chicken reaches 74°C/165°F in the thickest part. Add the cooled pineapple pieces and stir to combine.
Season with salt and freshly ground pepper to taste.