Heat oil in a wide pan. Sauté onions until golden.
Add ginger-garlic paste and green chilies. Sauté until aromatic.
Stir in chopped tomatoes and cook until soft and mushy.
Add bell pepper and cook for 2–3 minutes.
Add turmeric, pav bhaji masala, chili powder, and salt. Mix well.
Add cauliflower, peas, and mashed potatoes. Mash everything using a potato masher.
Pour in a splash of water as needed to get a smooth, thick consistency.
Let it simmer for 10–15 minutes, stirring and mashing occasionally.
Finish with lemon juice and fresh coriander.