Combine all ingredients, then using a food processor, blend smooth. Add additional water to make the sauce as "saucy" as you want it.
Once processed and any additional water has been added, taste for spiciness and add additional cayenne pepper powder as needed to get your preferred level of heat.
Notes
5 Tbsp tahini 4 Tbsp lemon juice 4 Tbsp olive oil 6 cloves garlic, crushed 4 Tbsp finely chopped fresh parsley or coriander leaves 1/2 tsp salt 1/2 tsp pepper 1/8 tsp cayenne 1/3 cup water