Warm vinegar (250ml) in a small saucepan and add mustard seeds (1.5 tbsp). Let sit for 15 minutes. Blend vinegar and mustard seeds with ginger (120g) and garlic (10 cloves) in a food processor.
Heat olive oil (30ml) in a medium saucepan over high heat for 1 minute. Remove from heat and add cumin seeds (1 tbsp), turmeric (1 tbsp), coriander seeds (1 tbsp), nigella seeds (2 tbsp), cloves (4), and chili powder (1 tsp). Fry for 20 seconds and then add mustard vinegar mix, chillies (6), and onion (1).
Bring to a simmer over medium heat then add the tomato (800g), apple or mango (1 kg), brown sugar (125g), and salt (30g).
Reduce heat to low and simmer gently for 1-1.25 hours, stirring occasionally. Pour inter sterlizied jars with metal lids.