Now add in the tomato paste mixed well in one cup water.add in the spices,coriander and potato(peeled and chopped).mix well.Add in 1 glass of water.mix.After 1 minute,add in the brains and cover.After 4 -6 minutes,shake the sufuria and let them cook again for another 2 minutes.when potatoes are soft,the curry is ready.serve with rice or chapati.