Cut the cooked meat into 5 mm slices. Stack a few slices together at a time and cut into 5 mm slivers. This does not have to be done too evenly.
Combine the black pepper, chilli powder, ground cumin, ground coriander, turmeric, vinegar, ½ tsp salt and 2 tb water in a small cup. Mix and set aside.
Put the oil in a large frying pan over medium-high heat.
When hot, put in the cumin, mustard and fenugreek seeds.
As soon as the mustard seeds begin to pop, put in the green pepper and onion. Stir and fry until the onion has browned quite a bit and the mass of vegetables has reduced.
Sprinkle about 1/8 tsp salt over the top and stir.
Add the meat and the spice mixture from the cup. Stir rapidly on the same medium-high heat for a minute or so until the meat has heated thorough.
Add the Worcestershire sauce and stir to mix.
