Bring a pot of water to the boil and cook potatoes, cauliflower, peas and green beans until soft. Drain, but reserve water. Mash vegetables.
Heat oil. Add onions, chiles and bell pepper. Saute for 5 minutes until softened. Add ginger garlic paste and cook for 1 more minute.
Add turmeric, chile powder, masala powder jaggery, tomatoes, 1 1/4 cups cooking liquid and salt. Bring to a boil. Reduce to a simmer and cook for 15 minutes on low heat, stirring occasionally.
Cook for 5 minutes on high heat, until tomatoes are softened.
Add mashed vegetables and 1/2 cup water (or more of reserved cooking liquid if you still have).
Bring to a boil. Reduce to a simmer and cook for 15 minutes on low heat, stirring occasionally.
Add butter, lemon juice and cilantro. Stir to combine.