In a mixing bowl, whisk besan, salt, turmeric powder and buttermilk together. Transfer it in a saucepan along with one liter or 4 cups of water and start boiling on low heat.
Meanwhile slice and chop spinach and radish.
Let the buttermilk cook on low heat until it starts boiling, and then settles down.
Now add the spring onion, and garlic to the boiling mixture of buttermilk.
Allow it to cook on simmer for 45 minutes or an hour and continue stirring in between.
Remove from heat and set aside.
Make Tadka
Heat butter in a pan and add aseftida, garlic and dry red chili. Saute until garlic is golden.
Turn off the heat and add kahsmiri red chilli. Pour this tadka over the saag. Mix well.