Wash lemons, dab dry and cut them into 4 to 8 pieces and set aside.
Roast salt in a dry pan till it crepitates and set aside.
Dry fry fenugreek till it turns brownish.
Roast mustard till it splutters. Fry red chilli and asafoetida in 2 tsp oil.
Grind salt, red chilli, asafoetida, mustard and fenugreek into a fine powder.
Mix the powder with lemon thoroughly.
Temper with mustard fried in oil.
Mix and press the pieces down so that oil floats on top, which prevents spoiling.
Mix every day.
It is ready to consume in 3 - 4 days.