Dry roast coriander seeds & cumin seed.Add ginger,garlic,fried onion ,dried chilis, anaar-dana and grind to coarse paste.Mix this paste,salt and curd to minced mutton .Leave it for minimum 30 minute (or 2 hour max).
After a good marination,mix chopped tomato to it.Leave it aside for 15-30 min only.
Heat oil in a heavy bottom pan at medium heat.Add slowly marinated mutton to it.Now stir it contentiously for 2-3 min.Keep in mind that to cook perfect keema you need to maintain a medium temperature(170 F).Slow cooking of your mince makes it perfect , if you make your temperature high enough than it will be chewy and loose its moisture.
Cook the keema uncovered for about 8-10 min till it almost done.Now break an egg in a bowl and mix well with a spoon.Add cornflour to it and mix.Add this mixture to keema stirring it slowly with your spatula.Mix well and let it cook for another 5 min.Adjust salt.