Boil potato, carrot and cauliflower in two cups of water till nearly done. Add French beans and peas and boil further for five minutes. Drain and cool.
Heat five cups of water, bring it to a boil, add vermicelli, salt and two tablespoons of oil. Cook for one minute or till slightly underdone.
Drain, refresh under cold water and keep aside. Heat remaining oil in a pan, temper with mustard seeds and curry leaves. Add urad dal, ginger and onion. Sauté well till the onion turns light brown.
Add green chillies and stir. Add the cooked vegetables, green capsicum, turmeric powder and sauté for four to five minutes. Add cooked vermicelli, salt and stir gently.
Cook for five to six minutes. Remove from heat. Mix in lemon juice and serve hot.