Heat oil and splutter mustard urad dhal.
Add curry leaves and hing.
Add the halved pearl onions and sauté till golden.
Add the berries and sauté for a minute.
Soak tamarind and extract juice.
Add the tamarind juice, salt, turmeric and sambar powder.
Allow it to boil on low flame. Keep the pan covered until oil separates.
Serve hot with rice and accompany it with appalam.