Heat oil in a pan. Fry curry leaves, green chillies and small onions for 2 minutes. Then add the chopped spinach and salt.
Saute for 2 more minutes till the spinach gets cooked. Take it off the flame and keep it aside for now. Meanwhile, add yogurt in a mixing bowl. Whisk it till it becomes smooth. Add salt, coriander cumin powder and mix it together. Add the sauteed spinach mixture in it. In a tadka pan, temper mustard seeds, urad dal and dried red chillies. Pour this tadka over the yogurt. Give it a good mix.
Refrigerate it till it's time to be served.
You can use regular onions instead of baby onions. Add grated cucumber to the raita to give it a different taste.