Wash Karondas twice with water. Place them in a plate or strainer to dry and drain out water. Now cut these Karondas into 2 halves, if there is a black seed in any Karonda then cut it out with a knife.
Grind yellow mustard and Saunff to make a coarse powder.
Pour oil in a pan and heat then turn off the gas. Put Heeng, turmeric powder, salt and Karondas in hot oil. Also add Saunff powder, yellow mustard powder and red chilly powder to these Karondas. then mix properly. Karonda Pickle is ready. Fill this pickle in a glass or plastic container and store.
If you want to keep the pickle in the sun, then keep the container for 4-5 days out in the sun. Stir pickle with a spoon once everyday. Even if you are not able to keep it in the sun, stir pickle everyday. Karonda pieces will become soft after 4-5 days. Now add oil to the pickle enough to submerge it fully.
You can take out some Karonda Pickle and have it whenever you feel like up to 1 year.