1.Peel alternate lengthwise strips of skin from eggplants, chop eggplants coarsely. Place eggplant in medium non-metallic bowl, sprinkle with salt, mix well. Stand 10 minutes. Rinse and drain eggplant well, drain on absorbent paper.
2.Heat oil in large frying pan, cook mustard seeds, stirring, until they begin to pop. Add onion, garlic, fresh chilli and cumin seeds; cook, stirring, until onion softens. Add tomato, cook, stirring, about 2 minutes or until tomato softens. Stir in eggplant and remaining ingredients, simmer, covered, over low heat, stirring occasionally, about 25 minutes or until eggplant is tender. Cool 15 minutes, then blend or process eggplant mixture until pulpy.
3.Spoon relish into hot sterilised jars, seal immediately. Label and date jars when cold.