1. In a medium-sized saucepan, combine the mustard seeds, white vinegar, and water. Bring the mixture to a boil over medium heat. Once it starts boiling, reduce the heat to low and simmer for 10 minutes. This will soften the mustard seeds and allow them to absorb the flavours.
2. Add the granulated sugar, red onion, minced garlic, ground turmeric, ground ginger, red chilli flakes, and salt to the saucepan. Stir well to combine all the ingredients.
3. Simmer the mixture over low heat, stirring occasionally, for approximately 35 minutes or until the relish reaches a thick and jam-like consistency. Make sure to scrape the bottom of the saucepan to prevent the relish from sticking.
4. Once the relish has thickened, remove the saucepan from the heat and let it cool to room temperature.
5. Transfer the Spicy Mustard Seed Relish into sterilised jars and seal them tightly. Store the jars in a cool, dark place or in the refrigerator.
6. The Spicy Mustard Seed Relish is ready to be enjoyed immediately, but the flavours will develop and intensify over time. Allow the relish to mature for at least 24 hours before using it to fully enhance the flavours.

Note: The relish can be stored in airtight jars for up to 3 months when refrigerated.

Now you have a delicious and versatile Spicy Mustard Seed Relish to add a zing to your meals. Enjoy it as a condiment, dip, or ingredient in your favourite recipes!