Wash the pepper and wipe them clean removing all the moisture from them.
Cut the peppers into thin two lengthwise slices , you can remove the stem of can leave the stem intact.
In the coffee grinder coarsely grind the mustard seeds and fenugreek seeds (You can get this mix in the Indian store ready made, it is called Rai-Methi sambhar for pickle.
Add the turmeric powder, mustard/fenugreek mix, salt and cayenne pepper.
Add lime juice. Mix well, you can serve it right away.