Heat oil in a kadai or non-stick pan in medium high flame.
Add mustard first, followed by urad dal, cumin seeds and asafoetida
Add onion once the urad dal starts to change color. Make sure not to burn the cumin.
Stir-fry until onion turns soft, add garlic and cut tomato for 1 minute.
Add the spices and only the stem of the chard. Do not add salt yet. (see notes)
Sprinkle a little water if too dry. Stir fry for 2 minutes.
Now add the cut chard leaves and mix it together. (See Notes for cutting tips)
Add ⅛ cup or less of water to cook the stem.
Reduce flame to medium low, cover and cook for 3 to 4 minutes
Now add salt an needed, the leaves will be wilted and the stem will be softened.
Stir-fry until most or all of the water evapotates.
Transfer to a heat resistant container.
Serve with rice and curry or as a salad.