Pressure cook peeled, chopped potatoes and other chopped veggies together with little water, upto 3 whistles in pressure cooker.
Mash nicely with a potato masher and set aside.
Heat a broad pan with butter, fry onion until translucent.
After that add ginger garlic paste, fry till raw smell of the ginger garlic paste goes off.
Then add the capsicum and fry for a minute.
Following it, add tomatoes, salt, pav Bhaji masala and red chilli powder.
Fry till tomatoes turns soft and mushy.
Then add all the veggies, stir well.
Simmer for 5 to 7 minutes and mash with a ladle so that all the veggies get mixed well.
Finally add butter if desired. Bhaji is ready now to serve with pav.