Wash and cut the kovakkai into 4 to 5 thin pieces lengthwise. Add turmeric powder and salt and mix well. Keep it aside.
Chop onion finely.
In a kadai put the oil and add mustard. When it pops up, add urad dhal, jeera, asafotida powder and curry leaves. Fry till the dhal turns light brown. Then add chopped onion and fry till it is transparent. Now add kovakkai pieces and fry for few seconds. Add sambar powder and mix well. Close with lid and cook on medium flame. (No need to add water). Stir now and then and keep it on stove till it is soft.