Wash the Swiss chard thoroughly and separate the stems from the leaves. Chop the stems finely and cut the leaves into small pieces.
In a pan, heat coconut oil over medium heat. Add mustard seeds and let them splutter.
Add chana dal, slit green chili, dried red chilies, and curry leaves. Sauté until the dal turns golden brown.
Add chopped onions and garlic. Sauté until the onions turn soft and translucent.
Add the chopped chard stems first, as they take longer to cook. Stir-fry for 2–3 minutes.
Add the Swiss chard leaves, turmeric powder, and salt. Stir well and cook for about 5 minutes until the leaves wilt and become tender.
Sprinkle grated coconut over the poriyal, mix well, and turn off the heat.
Enjoy Swiss Chard Poriyal as a side dish with steamed rice and sambar or rasam.