Take the mustard seeds and fenugreek seeds in a microwave safe bowl. Heat in high, for 2 minutes, until a nice aroma comes from the seeds. Keep aside and let them cool.
Grind into a fine powder.
Take enough oil, with mustard seeds, for tempering. Cook in high, for 2 minutes.
Add the garlic cloves, diced green chillies. Cook everything for 5 minutes in high(give a stir in between).
Add red chilli powder, amchur powder, mustard-fenugreek powder, salt and toss everything gently. Cook for 5 minutes in high, until the garlic and green chillies, get well coated by the spice powder. Keep aside and let them cool completely.