Blend the ingredients: In a blender or food processor, combine the garlic, tahini, olive oil, lemon juice, lemon zest, salt and cumin. Blend until smooth. The mixture will be very thick at first.
Adjust consistency: With the blender running, slowly add water 1 tablespoon at a time until the sauce reaches your desired consistency. For a pourable sauce, you may need about ⅓ to ½ cup of water total. Add the fresh parsley and pulse until smooth.
Season and store: Taste and adjust with more lemon juice or salt, if desired. Transfer to a jar or airtight container. The sauce can be refrigerated for up to 5–7 days.
Serve: Use as a drizzle for grain bowls, roasted vegetables, falafel, grilled meats, or as a dip!