If using canned corn kernels then drain well. If using frozen then defrost it, take into microwave safe bowl along with few teaspoons of water and cook in microwave for 3-4 minutes.
Take chopped tomatoes and cashews in a blender.
Make smooth paste out of it without adding any extra water. And keep it aside.
Heat 2 teaspoons of oil in a pan on medium heat.
Once hot add capsicum. Saute for 2-3 minutes till they are only 80% cooked. Meaning capsicum should be still crunchy. Remove them to a plate and keep it aside.
In the same pan heat remaining 1 tablespoon of oil.
Once hot add chopped onions. Sprinkle some salt and mix. Cook till onions are light brown in color.
Now add ginger paste and garlic paste. Mix and saute for a minute.
Now add prepared tomato-cashew paste.
Cook till all the moisture evaporates and it becomes like a thick paste. Do stir in between.
Add turmeric powder, red chili powder and coriander powder. Mix well and cook for a minute. You will notice oil is separating from the sides.
Now add water. Stir well to make the gravy consistency. Bring it to a boil.
Now add garam masala and kasoori methi. Mix well.
Also add boiled corn kernels and cooked capsicum.
Mix well and let it simmer for 3-4 minutes.
If the gravy is too thick then you can add little more water and simmer.