Put dried chickpeas in a bowl and cover with water by a few inches. Soak 12-24 hours, making sure chickpeas stay completely submerged in water the entire time.
Preheat oven to 375 degrees. Line a baking sheet with unbleached parchment paper and grease the paper with olive oil.
Drain the chickpeas, and add to a food processor with garlic, onion, spices, salt and pepper, baking soda, lemon juice, parsley and flour. (Use a meat grinder if you have one.) Pulse the mixture, scraping down the sides as necessary, until it looks like couscous. The mixture will be quite crumbly.
Form the mixture into about 20 balls, 1 ½ inches each. Press down on the tops to flatten them into thick patties. You can add a little extra flour if they are not holding together. Place them on the prepared baking sheet. Brush the tops with oil.
Bake for 15 minutes on each side or until golden. You can fry them in oil, as well (not as healthy.)
Blend all the sauce ingredients in a blender adjusting water to achieve right consistency. You want a thin sauce.
Serve falafel with tahini sauce in a pita or lettuce leaves. Chopped tomato and cucumber salad is a nice accompaniment.