Heat a pressure cooker with oil. Splutter mustard seeds. Add onion and sauté until it becomes soft. Add tomato and sauté until it becomes soft. Add radish, kulambu milagai thool and salt. Sprinkle some water (1/4 cup approx). Close the lid and cook it for 1 whistle.

Once pressure releases, open and sauté the curry in medium flame until it gets thicken.