This relish is of south Indian origin and is known on the subcontinent as tomato kasaundi. It is traditionally served as a condiment with breads and fish dishes, but you will find its flavour extremely versatile and easily adaptable to a variety of uses, not restricted to Indian-style preparations. It has a characteristic sweet-sour, spicy flavour with the chilli component being very mild on the palate, much like pepper. Serve it simply as a dipping sauce with vegetable antipasto or fried savoury pastries, or stir it into lentils or through noodles or pasta.