Add the whole lemons in to pressure cooker along with 2 cups of water. Pressure cook it for 1 whistle and let the pressure subside.
Next remove the lid and take out all the cooked lemons. Chop each of them in to quarter and remove all the seeds
Take the lemon pieces in a wide bowl. Add roasted mustard powder and roasted fenugreek powder.
Next add salt and red chilly powder too. Squeeze in a lemon over it.
Next mix everything well gently and heat a pan adding oil, mustard seeds and hing.
Let it splutter. Let the tempering cool down to room temperature, then pour it over the pickle. Mix well.
Instant lemon pickle is ready. Let it rest for few days so that all spices are absorbed by lemon.