Chop the ivygourd into long pieces. Heat oil in a pan. Add the onion and green chillies. Saute till the onion turns slightly brown.Add the ivygourd and salt. Mix well. Add few drops of water. Close the lid and allow it to cook.Keep sauteing in between. Cook well till the ivygourd is slightly brown. Switch off the flame. Add the tamarind. Allow it to cool and grind it to a paste.