Place a thick bottom wide kadhai on the gas and heat 3 tbsp of butter in the kadhai.
When the butter melts, add cumin seeds in the kadhai and saute till it splutters.
Add finely chopped onions in the kadhai and stir and cook till it turns a translucent and golden brown in colour.
Then, add a tbsp of ginger-garlic paste or grated and finely chopped green chillies in the pan and saute till the garlic leaves its raw smell.
Now, add finely chopped tomatoes in the pan.
Mix all the ingredients nicely in the kadhai and cook till the tomatoes turn soft and mushy.
Add half tsp of salt in the pan, it helps in cooking tomatoes quickly.
When tomatoes are cooked perfectly, add in chopped capsicum or bell peppers.
Saute the capsicum for 2 to 3 minutes and leave it half cooked as it feels crunchier while chewing.
Then, add haldi, red chilli powder, pav bhaji masala, and garam masala.
Mix all the dry spices with the veggies nicely and add an extra tsp of butter at this stage. This way, spices get cooked in butter and a nice aroma of butter comes from the veggie.
After a few minutes, add the boiled and cooked veggies from the pressure cooker and add all the vegetable stock. Do not discard the vegetable stock.
Mix the boiled veggies with the spiced onion-tomato in the pan.
Now, with the help of a potato masher or a large slotted spoon, mash the veggies in the pan. Mash the veggies till you reach the desired consistency.
Finally, add salt as per your taste and freshly chopped coriander leaves.
Spicy and tasty bhaji is ready to be served hot with butter toasted pav.