Mutton curry wth home made garam masala

Ingredints
Mutton : 2lbs
onion - 1 big chopped
tomato - 2 chopped
garam masala ( grind pata (2) , lavanga(6), elachi(4), pepper corns (10) ) - grind and use 1 tsp spoon for this
ginger garlic paste - 2 tbsp
red chili powder - 1 tsp
coriander powder - 2.5 tsps
cumin seeds - 1 tsp
turmeric
salt

Method : 
Heat oil in a cooker, add onions fry till golden brown
now add mutton and fry till water is evaporated
now add ginger garlic paste
now add red chili powder, coriander powder, cumin seeds, turmeric and salt n mix well
now add tomato n mix well
add water n close the lid and give three whistles. let it cool down.
now take the lid and cook well until oil is separate.
now add garam masala powder - 1tsp
squeeze 1/2 lemon
add little water n cook on slow flame for more 10 mins
garnish with coriander leaves.