Heat oil in a pan and add the mustard seeds. When the mustard pops, add the chana dal and cumin seeds. Saute till brown. Add chopped onion, ginger and garlic and turmeric powder.
Saute till onion turn slightly soft, about five minutes. Now add the frozen mixed veggies. Give a mix ,close the lid and mix occasionally and cook till the veggies turn soft. You can splash little water while cooking to avoid burnt bottom.
Once the veggies are cooked completely, add the fresh coconut, red chili powder, coriander powder, garam masala and salt.
Saute for another five minutes, taste and adjust the seasoning . Finally finish it off with some lemon juice and coriander leaves.
Serve the veggie stir fry with rice, rasam, pickle and yogurt.