In a pot heat oil. Add mustard seeds. When mustard seeds starts to sputter add turmeric powder, garlic and asafoetida.
Add chopped onion. Saute for a minute.
Add chopped lal math (Amaranth), red chilli powder and salt.
Cook it on a low heat for 10 minutes in a covered pot. No need to add water as the water released from the lal math (Amaranth) will be enough to cook the vegetable.