Heat the oil in a pan over a low-medium heat. Add the mustard seeds and cook until they start to pop.

Next, add the garlic, stir, and cook for a minute. Then add the water, tomato paste, onion powder, cumin, and coriander. Stir to combine.

Add the cabbage to the pan and turn to coat in the spiced mixture. Cover and cook until the cabbage is cooked, about 10 minutes.

If excess liquid remains, increase the heat and cook until it has been absorbed. Taste for seasoning and add generous amounts of salt, pepper, and cayenne, if using.

Transfer the chutney to a food processor. Pulse a few times - you don't want it to turn to mush, but to have a uniform texture.

Spoon the chutney into a bowl or storage container and allow to cool. Store (covered) in the fridge for up to a week.