I'm a newbie here and perhaps this is a dumb question BUT what is it the 'closest one' to? i.e. given that the basic curry sauce is only work-in-progress within a UK indian restaurant/take-away. You can't order a portion of basic curry sauce, can you? And be sure they haven't added anything. Pure samples would be useful in order to have a reference point to aim at. Better still, get half a dozen samples from as many take-aways, in order to assess consistency, and have even more to go on.
Moving on to the next stage of cooking, whether it be Chicken Korma (one of my favorites) or any final dish, surely adds a whole load more uncertainty as to whether 'stage 1' - the basic sauce is as good as my suggested sample of six professionally made sauces.
Regards
George