Heat oil in a kadai and add mustard seeds, cone it pop up add fenugreek seed, followed by curry leaves, green chilli, garlic ginger and crushed pepper.
Fry for 2-4 minutes in medium flame. If you pressure cooked the meat, squeeze the meat well enough to remove all those water. Keep the stock separate.
Make a paste using vinegar, meat stock and other powders. Add this masala paste to the oil mixture and stir well for another 3 minute.
Fry meat in this masala for another 5 minutes. Add the remaining stock bring this to boil and reduce the flame to low and let the beef absorb that masalas.
Once you are satisfied with the consistency you can transfer this pickle to a clean air tight jar and place a sesame wet cloth on top of the jar and close the lid tight. That is it your pickle jar is ready for you.