Combine the chickpeas, red onion, garlic, cilantro and parsley in a food processor. Process until broken down but still a little chunky.
Transfer the mixture to a bowl and add the remaining ingredients (through baking soda). Mix well.
Form the falafel mixture into patties. I like doing small, thick patties - it makes it easier to flip them and they hold together better. Plus, you get a generous bite!
Place the patties on a plate, then cover and refrigerate for at least 1 hour. Or, you can stick the patties in the freezer for 20-30 minutes. This helps them set up so they'll hold together better.
Preheat the oven to 400. Remove falafel patties and space them out evenly on a baking pan sprayed with cooking spray.
Bake at 400 for 20 minutes, then flip carefully. If any of the patties fall apart a little, you can carefully use the spatula and your hand to smush them back together. They firm up by the time they are finished baking.
Bake another 10-15 minutes, until well browned and firm.
In the meantime, make the tahini sauce. Mix the tahini, lemon juice, 2 tablespoons of water and a dash of salt and pepper in a small bowl. Add additional water, a tablespoon at a time, if needed, to get the sauce to a drizzling consistency. (It will depend on the thickness of your tahini.)
Once they are finished cooking and nicely browned, remove the falafel patties and let cool for a couple minutes on the pan. This helps them finish setting up so they hold together.
Serve in the pitas with the tahini sauce, and enjoy!