Zest the lemon, then squeeze the lemon juice directly into a high-speed blender or food processor, making sure you remove any seeds.
Add the tahini, garlic, parsley, and cilantro. Add the salt and black pepper, and ½ cup of water to start.
Pulse or blend the ingredients until well combined. The mixture will be quite thick at this point. Add more water 2-3 tablespoons at a time until it reaches a thick but pourable consistency (for reference, we used ¾ cup total).
Once you’re happy with the consistency, give your lemon herb tahini a taste and adjust the seasonings if necessary. Add more salt, pepper, or lemon juice as needed.