Preheat your oven to 450° F. Preheat your crust, if necessary.
Heat the oil in a pan over medium-high heat. Add the onion and cook for about 5 minutes, or it begins to brown. Add the garlic and cook for another minute or two. Then add the chopped spinach and cook for just a minute or two more, until it wilts.
Spread the tomato sauce over the crust, and then top with the spinach mixture. Layer on the rest of the ingredients with the exception of the tahini sauce.
Cook for 10-12 minutes.
Drizzle on the tahini sauce and slice into 8 pieces. Serve hot.