Add all of the ingredients except for the yogurt to your food processor and blitz until smooth. Scrape down as necessary and blitz again until the mixture is smooth. You will have flecks of herbs.
½ cup tahini, ¼ cup fresh parsley, ¼ cup fresh cilantro, 1 small clove garlic, ¼ cup lemon juice, 1 tablespoon olive oil, 1 teaspoon lemon zest, ½ teaspoon salt, ¼ teaspoon ground black pepper
Add ¼ cup of the yogurt, sour cream, or water and blitz again for 10 seconds.
¼ cup yogurt (or Greek yogurt, sour cream, or water)
Check the consistency and taste. Add more yogurt or water, lemon juice, salt, or pepper, as desired.
Serve immediately or store in a air-tight container or wrapped in plastic wrap in the refrigerator for up to one week.