Boil pasta in water with little salt. Cook till pasta is soft. Strain pasta and keep little water from pasta in a bowl aside.
Heat the pan/ wok/ karahi at medium heat. Add oil. Once oil is hot. Add curry leaves, cumin and mustard seeds.`
Sauté and add onions, potatoes and salt. Mix well, cover and cook for 3-4 minutes or till potatoes are soft.
Stir couple of times in between. Once potatoes are soft add boiled or frozen veggies, tomatoes and mix them well.
Cover and cook till tomatoes are very soft and mushy. It may take 7-8 minutes. If mixture is getting dry add some reserved pasta water at this time.
Once tomatoes are soft enough add turmeric powder, red chilly powder and coriander powder.
Mix them well and stir boiled pasta. Mix gently. Now pour some butter, lemon juice, coriander leaves and if you like little sweet taste add some tomato ketchup.
Mix everything gently. Pasta is ready to serve.