Add the tahini, lemon juice, and water to the bowl. Whisk vigorously for 1 to 2 minutes until the sauce becomes light in colour and very smooth. If it dries up and feels firm, keep whisking. You may add a few tablespoons more of water as needed.
Season with salt and pepper, then garnish with chopped parsley.
Notes
Use high quality tahini when making this sauce, and ensure it is not bitter. You can make your own tahini if you don't have it.
You can adjust the garlic, lemon juice and salt to your taste.
Store it in an airtight container and in the fridge for up to a week. It will thicken in the fridge, you can simply add a few tablespoons of water and whisk to loosen it before using.