Hi 976 made this the other day with what's called a mutton back strap, a long very lean fillet, and slow cooked it like you siggested for 4 hoyurs till tender. Then made to spec the curry and was very pleased with the results. Its my first Bhuna and it was very full of flavour from the tomatoes, peppers, onion and of course the mutton. It had a subtle level of heat and i garnished with a couple of extra cooked through green finger chilli's. I will definatley make this again and will definately be using more mutton (photo's next time)
Cheers 976!
Cheers 976!