Choose ripe yet firm star fruits, wash and slice them evenly.
Roast mustard seeds, fenugreek and fennel seeds, then grind them into a coarse powder.
Add salt, turmeric, chilli powder and the roasted spice mix to the star fruit slices.
Heat mustard oil, temper with mustard seeds and asafoetida, then pour it over the spiced carambola mixture.
Let the pickle marinate for 2-3 days in sunlight, stirring occasionally before storing it in an airtight jar.