In a small bowl, stir together the tahini, greek yogurt, tamari, and lemon juice until smooth. One tablespoon at a time, add warm water to thin out the dressing as needed– you want it to be creamy and thick, but still drippy enough to drizzle. I usually only need about 1-2 tablespoons, but this will depend on the consistency of your tahini. Add salt and pepper, to taste. Set Aside.