Wandering fruitlessly through the myriad of 'Balti' threads on here today, I inadvertently came across the answer to my own question at
Post #5 above.
I found in the
Glasgow Balti thread from the BB1 the following (my emphasis):
Glasgow pre cooked chicken 8 PIECES
1/4 GREEN Diced Pepper
1/2 SMALL ONION FINELY CHOPPED
1 SMALL FINELY CHOPPED TOMATO
GOOD PINCH Fresh Coriander
1 TSP Garlic Ginger paste
1 TSP Tomato Pur?e
1 TSP METHI
1 TSP GREEN CHILLI SAUCE (recipe below)
1 TBL spoon RED SAUCE MIX (recipe below)
1 TBL Patak's Mixed PickleTHE GLASGOW Base Sauce
I didn't take a great deal of interest in these topics at the time, but that bit of info sorts things out a little and suggests that the inclusion of Pataks Mixed Pickle is probably common to 'Balti' meals around this neck of the woods.