1. Heat about 3-4 tbsp of butter (more the merrier), add onions and saute them till soft.
2. Add capsicum and saute for another min.
3. Add ginger and garlic along with chillies. Saute another 2 min.
4. Add the tomatoes and mix well, till soft.
5. Add the puree along with the spices (including black salt if using) and mix well another 5-10min till the raw smell of the puree goes away.Season with salt.
6. Add the boiled vegetables along with the potatoes, mix well and if the gravy is thick add little water.
7. Let it come to a boil and then reduce and let it warm in simmer.
8. Meanwhile heat a non-stcik pan and grease it with butter.
9. Take a bun/Pav, slice it in half and cook with butter until lightly brown on both the sides.
10. Seve hot with the bhaji(gravy) garnish with cilantro and lemon wedges.

Note:
Pav Bhaji Masala is a blend of approx 10 spices like cumin,corainder,cloves,cinnamon,red chilly,black pepper,mango powder,turmeric,cardamom,coriander seed.

Courtesy: http://chefinyou.com/