Heat butter in a pan. Add onion and sauté for a minute. Add ginger-garlic paste, mix and sauté well. Add tomatoes, mix and add spices and mix well. Cook on low heat for 5-7 minutes. Add cauliflower, capsicum and green peas and mix well. Add pav bhaji masala and mix well. Reduce heat, add some water, cover and cook till vegetables are done. Add potatoes. Mash well with a masher.

Add some water, mix, cover and cook for 5-7 minutes. Slit pavs and apply butter on them. Heat 1 tablespoon butter on a non-stick tawa, sprinkle some chopped coriander and pav bhaji masala on it, place the pavs and roast them. Transfer the bhaji in a serving bowl. Place the bowl on a serving platter and serve immediately with toasted pav.