In a blender, add 200 grams of fresh or frozen blueberries, 500 grams of chilled plain yogurt (dahi), 100 grams of sugar or honey (adjust to taste), and a pinch of cardamom powder. You can also add a few ice cubes if you prefer a chilled lassi.
Blend all the ingredients together until smooth and creamy. If the lassi is too thick, add a little cold water or milk to adjust the consistency.
Pour the blueberry lassi into glasses and garnish with a few fresh blueberries and a sprinkle of cardamom powder on top. Serve immediately.