In a medium bowl, pour ½ cup of cold water.
Add garlic powder, 1 tablespoon lemon juice, salt, and mix.
Add the tahini. Using a whisk or a fork, mix until thoroughly blended. Taste and add salt, lemon, and garlic powder, if needed.
Slowly add more water, 2 tablespoons at a time, whisking after each addition until smooth.
Keep adding water slowly until the sauce can drizzle from a spoon.
Transfer the tahini to a serving bowl, and if you like stir in fresh chopped parsley.