Tomato Cucumber Raita

Ingredients

1 cup cucumber
1/2 cup tomatoes
2 cups whisked curd
1 tsp oil
1 tsp mustard seed
1 tsp black gram dal / urad dal
1 tsp salt
1 tsp cumin powder
2 green chillies
pinch of asafoetida/ hing
7 to 8 curry leaves