Heat a pan with mustard oil.
Add cumin seeds and mix well.
Fry the onions for half a minute.
Add potatoes, garlic, dry red chilies, ginger, green chilies, turmeric powder, Kashmiri red chili powder, coriander powder, salt, and mix well.
Fry on high flame until onion is light golden (5-6 minutes).
Add the tomatoes and fry for 1 minute.
Cover the pan and cook on low flame for 10-12 minutes or until potatoes are cooked through.
Add spinach and stir gently. Cook for another 5 minutes.
Garnish with coriander.