A popular andhra region recipe combined with sorrel/gongura leaves and mutton...
1.If the flavor is too tangy then reduce the amount of sorrel leaves or increase the quantity of onions in the curry the next time you try the dish.
2.One can add red chilli powder while cooking gongura to reduce the sour taste.
3.Also try my gongura chicken recipe. And the same procedure can be applied to gongura mutton too.