I find I only get decent BIR style results if I use a curry base. Taz base worked very well for me.
As I'm yet to move into a new house, I don't have curry base, so need to cook non-BIR from scratch.
I recently saw this video on cooking a Pakistani Karahi dish, which I am going to try.
https://youtu.be/4PMmH2-5wJMAlthough he does use tinned tomatoes, the amount isn't huge, so maybe that would produce a less sweet tasting dish? The technique is straightforward and nothing unusual about any of the ingredients.
If you have an electric pressure cooker, I have been getting great results with this recipe.
https://twosleevers.com/instant-pot-butter-chicken/Probably really easy to adapt to regular pressure cooker too. The sauce it produces is initially too thin when blended with the stick blender. I cook it ahead of time, let it cool for an hour or more, then warm it through, adding butter and / or cream and it thickens up nicely. I follow this recipe straight when cooking for the missis, but have experimented with mix powder, fresh chilies, fresh coriander stalks, chilli powder instead of cayenne and the results have been very tasty. No onions seems weird but it works.
Robbo