Thoroughly wash and dry the limes. Cut each lime in half, through the middle, then cut each half into quarters, so you end up with eight half wedges from each lime. Remove the seeds.
Pack the limes into a large sterilized jar, sprinkling over the salt at the same time. Seal, and leave to stand in a warm place for two weeks, or until the limes have turned brown and softened.
to make the pickle
Heat a small frypan over medium heat. Add the fenugreek seeds and toss gently until the seeds start to colour and become aromatic. Remove from the heat, allow to cool then grind to a fine powder.
Transfer the lime mixture to a heatproof bowl.
Heat the oil gently in a small frypan and add the chilli powder, crumbled chillies, fenugreek, turmeric, mustard seeds, and asafoetida, mixing well. Cook, stirring constantly for five minutes or until the oil is very hot. You must be very careful not to burn the spices, but the oil must get very hot for this dish to work.
Pour the oil and spices over the lime mix and stir well. Cover and allow to cool. When cooled, pack into a sterilised jar, making sure the oil completely covers the limes. Seal and store in a warm place for at least two weeks, although longer is preferred. A sunny spot in the garden, or even on the roof would be good. There is no need to do anything to the pickle before opening it to consume.
notes
Make sure that you dry the limes after washing. You do not want to introduce moisture into this dish for such pickling to work safely.
This recipe takes one month from start to finish, minimum.
Always remove pickle from the jar to serve. Remove enough to serve and place into a serving dish.
Once opened, refrigerate the pickle. It will last several months if stored this way. Allow pickle to come to room temperature before consuming.