All you need to do is roughly cut up your plum tomatoes, then sprinkle with salt. Preheat a pan, and add a little oil along with your mustard seeds, curry leaves, dried chilli and garlic. Fry until the garlic is golden brown, then remove from the heat and pour in the tomatoes, and add the red or white wine vinegar. Allow to spit and a sizzle for a bit, then put in a bowl and season.