To make the tahini. Combine all ingredients and 1/4 cup water in a blender and blend until smooth. If needed, add water to thin the sauce as desired. Season to taste with salt. To make the falafel. Add the veggies to a food processor and pulse until finely chopped. Add the chickpeas, flour, sesame seeds, garlic, cumin, cilantro, and a pinch each of salt and pepper. Pulse until the mixture is combined and mostly smooth. If the mix is dry, add 1 tablespoon water at a time until it holds a ball. Roll the dough into rounded tablespoon size balls, then gently flatten them down into 1/2 inch patties.Preheat the the broiler. Heat the olive oil in an oven-safe skillet set over medium heat. Add the falafel and cook 3-4 minutes per side, until deeply golden and crispy. Remove from the heat. Add cheese to each, then place the pan in the oven for 1-2 minutes to melt the cheese. Watch closely. To make the harissa oil. Combine all ingredients in a glass jar. Season to taste with salt. To assemble, spread the tahini on warmed naan, add lettuce, the falafel, and a spoonful of harissa oil. Top as desired with herbs, onions, and any amounts of additional sauce. Enjoy!