Slice the Zucchini into rounds, sprinkle with salt, and macerate for 30 minutes.
Drain off exuded water from the Zucchini, pat the slices dry, then grill at moderately high heat to produce dark grill lines on each side of the slices.
Toast and then grind the coriander and mustard seeds and mix with the turmeric and powdered fenugreek.
Heat the vegetable oil in a pan over a moderate flame and then add the spice mixture. Cook until the mixture starts to froth and add the Garlic and Ginger.
Stir in the Zucchini and Vinegar. Cook until the Vinegar has all but evaporated then transfer the contents to a suitable container.