Chop the potatoes into bite-size pieces. Sprinkle some salt and steam the potatoes with skin for 15 minutes or till almost done.
Peel the cooked potatoes and set them aside to cool.
In a bowl mix together yogurt, ginger & garlic paste, red chili powder, turmeric powder, coriander powder, kasoori methi, lemon juice, salt, garam masala powder, and mustard oil.
Heat butter and cooking oil in a saucepan and fry the yogurt mixture for 2 minutes. Then add capsicum and cook for a couple of more minutes. Do not overcook the capsicum.
Now add steamed potatoes and cook in the tandoori masala for 5 minutes on low heat covered.
Finally, add cream and chopped coriander leaves and cook for 1 more minute. At this point, the preparation should be dry.
Serve hot with help of a toothpick by layering with capsicum alternately.