Add all the ingredients to a food processor or a blender and blend until smooth.
Serve immediately with your favorite Indian dish or as a snack with some naan bread, papadum, crudités, etc. I served it with some pakoras.
Keep leftovers in a sealed container in the fridge for 3 to 4 days.
Notes
I didn't peel the ginger root, but it's up to you.
Tahini can be replaced by oil, but I would add only 2 tablespoon of water.
Classic recipe is made with green chilli, but as I couldn't find it, I used cayenne flakes. If you don't like spicy food, omit the cayenne flakes or add less.