Sauté the Aromatics: Place a large, heavy-bottomed saucepan or Dutch oven over a medium heat. Add the chopped red onion and a splash of water and cook for 5-7 minutes, until the onion has softened and turned translucent.

Add Spices and Chillies: Add the minced garlic, grated ginger, finely chopped jalapenos, and mustard seeds to the pan. Cook for another 2 minutes, stirring continuously, until everything is fragrant. This step helps to bloom the spices and release their full flavour.

Combine All Ingredients: Add the diced pineapple, light brown sugar, apple cider vinegar, water, red chilli flakes, turmeric, and salt to the pan. Stir everything together until the sugar has dissolved.

Bring to a Simmer: Increase the heat and bring the mixture to a boil. Once it's boiling, reduce the heat to low, so the chutney maintains a steady, gentle simmer.

Simmer and Thicken: Let the chutney simmer uncovered for 20-25 minutes, stirring occasionally to prevent it from sticking. What works best for me is to stir every 5 minutes or so. The chutney is ready when the liquid has reduced and thickened to a syrupy consistency, and the pineapple pieces are tender.

Cool and Store: Remove the pan from the heat and let the chutney cool for about 15 minutes. It will thicken further as it cools. Carefully transfer the hot chutney into sterilised jars. For guidance on this, BBC Good Food has an excellent article on how to sterilise jars properly. Seal and store in the refrigerator.