Boil the sweet corns prior to cooking the poriyal, and keep them aside.
Cut all the vegetables needs for the dish, and keep them aside.
In a kadai, heat oil. Add mustard seeds, and cumin seeds and allow them to splutter.
When they splutter, add curry leaves and red chilli.
Add the chopped carrots, beet root and cabbage and saute for 2 minutes. Sprinkle a little water on the vegetables, cover and cook them for 8-10 minutes or until they are fully cooked through. Keep checking on the vegetables periodically, and sprinkle more water if necessary.
Add the boiled sweet corns to the vegetables.
Add salt to the cooked vegetables, and corn and mix well.
Mix well and cook for 2 minutes.
Add the grated coconut.
Mix well and cook for 1-2 minutes on medium flame.
Take the poriyal off the heat, and serve with rice or any dish of your choice.