Wash karonda and green chilies and wipe them well with a cloth.
Chop green chilies into medium thick roundels.
Slice karondas and scoop out the seeds(if the seeds are brown then you should remove them as they are hard and bitter,but if the seeds are white and tender then no need to remove them.
Optional step-You can steam karondas for 2-3 minutes ,steaming make them slightly soft but if you like crisp pickle then avoid it as I do.
Heat 1/2 cup of mustard oil to a smoking point and then let it cool down slightely.
Dry roast fennel seeds,fenugreek and mustard seeds and when they cool down then crush them and make a coarse powder.
Add the crushed spices in hot mustard oil.
Take a bowl and add karonda ,green chilies,salt and all the spices ,oil and mix well.
Keep it covered for a day.
Next day add the remaining warm mustard oil and mix.
Let it mature for a week and then start using.