Wash and pat dry the ladies finger and cut into desired bite size pieces.
Chop the onion and tomatoes finely and set aside. Heat a pan with the sesame oil and fry the cut ladies finger in medium flame stirring now and then until the ladies finger starts turning brown here and there and the viscous nature of it goes away. Keep aside.
Heat oil for tempering and splutter the mustard,add urad dal and the curry leaves. Add the chopped onion and fry till transparent.
In goes chopped tomatoes, add required salt, fry till the tomatoes turn mushy.
Add the fried ladies finger,sambar powder and turmeric powder and mix well.
Sprinkle some water if needed and mix well and cook covered in medium low flame. Water from tomato itself is enough for this to get cooked, if adding water just a tbsp of water is enough.
Stir in between for even cooking. After the ladies finger gets cooked, keep the flame in medium and let the masala get brown and oil oozes out form the curry. Turn the curry occasionally to get the browning effect. Top with oil if it sticks in the pan.