Normally one is to get a piece of charcoal red-hot, put it in a small metal cup, put some ghee on it to burn/smoke, and put it in the pot with the finished dal tadka curry. I don't have charcoal.  And even if I bought charcoal I don't have a gas burner to heat it.  I have IH burners (electric induction heating, which can't heat charcoal). 
Find a bowl that your curry fits into, and that in turn fits in a tall pot. Put the ghee in the bottom of the tall pot, and the bowl into the pot.  Put a tight lid and set to highest temperature for 5-15 minutes.  Observe the smoke if you have a glass lid and experiment to find the best results for you. This also warms up the curry if it is leftovers. I was worried about the unequal heat shattering my ceramic bowl, so I rested it on a small silicone trivet meant to be good for any temperature that the pot could reach. 