Cover 250g of peeled, diced potatoes, 120g of chopped cauliflower, 1 cup of chopped carrot, and 1 cup of peas with water. Simmer until very soft; drain, reserving the liquid.
Melt 3 tablespoons of butter. Add 1 teaspoon of cumin seeds; let them sizzle. Add ½ cup of chopped onion and cook until soft.
Stir in 2 teaspoons of ginger-garlic paste and 1 teaspoon of chopped green chili. Add 2 cups of chopped tomatoes; cook for 6-7 minutes until pulpy.
Add ½ cup of chopped green bell pepper; cook for 3 minutes. Stir in 1 teaspoon of turmeric, 1 teaspoon of Kashmiri chili powder, and 2 tablespoons of pav bhaji masala.
Add the cooked vegetables and 1½ cups of reserved cooking liquid. Mash thoroughly. Simmer for 10 minutes, stirring; loosen with water and season with salt.
Split 12 soft dinner rolls and toast in batches with 3 tablespoons of butter for toasting. Serve with the bhaji, 3 tablespoons of chopped cilantro and 1 lemon, cut into wedges.
