Wash the spinach leaves and cut them very finely. In a pan heat one tbsp oil and saute the spinach for 2-3 minutes adding a little salt and crushed green chillies. Set aside to cool.
Whisk the yogurt adding a little salt, cumin powder and sugar (if you like it slightly sweeter taste)
Mix the sauteed spinach. Add a little water if you want a thinner consistency.
Heat the remaining oil in a pan and add the asafoetida and mustard seeds. When they crackle, add the tempering to the raita.