Soak the saffron strands in 3 tbsps of lukewarm water for atleast half an hour. Similarly, soak the whole pepper, fennel seeds, poppy seeds, and green cardamom separately and almonds and cashews separately for 30 to 45 minutes.
After half an hour, peel the skin of the almond and drain the water from the other spices.
Now grind the almond, cashews, fennel seeds, poppy seeds, whole pepper, and green cardamom by adding ¼ to ½ cup of water into a smooth paste.
Take the evaporated milk in a pitcher or can. Add the ground paste, sugar, saffron water with saffron and rose essence. Mix thoroughly and let it sit in the refrigerator for about 1 to 2 hours so that the masala mix can incorporate well.
That's it. Thandai is ready. Serve chilled. I don't strain the milk. We like the ground spice mix. But if you want smooth milk, strain it before serving.
You can add pistachios and melon seeds along with cashews and almonds.
Instead of whole green cardamom, you can use ground cardamom.
Adjust the sugar and spices according to your preference.
I have tried thandai with white pepper instead of black. You can use either one or a combination.
Evaporated milk is not mandatory. You can use regular or whole milk. Boil it and let it cool before adding the ground paste.
Thandai is typically served chilled. So take the chilling time into account.