To accompany the Aloo Tikki and Vegetable Pakora that we ate over the weekend I made some mint sauce, but although it was OK it was most definitely not identical to that served in BIRs. When I made some more tikki, and also because I bought some Onion Bhaji, I decided to continue to work on the mint sauce, and when I ate it last night and today I was certain I had cracked it. I am afraid I can offer no exact quantities, but I am sure that these will be more or less obvious if you try to make it.
Ingredients (brands as used, but neither essential nor even particularly recommended) : Tesco Greek yoghurt (full fat), Coleman's Classic Mint Sauce, Ahmed mild Mango Chutney, Asda Home Baking Lime Juice, Water, Liquid food colouring (green). I would think there were about three tablespoonsful of yoghurt, a coffee spoon of mint sauce, about the same of mango pickle and lime juice; add the colouring drop by drop and stir until it is homogeneous and the desired colour, then dilute with tap water until the desired consistency is achieved. You could add a little ground red chilli, but I didn't.
** Phil.