Place dried chickpeas in a large Dutch oven and cover with water by at least 2 inches. Stir in baking soda and soak overnight (at least 18 hours or more if chickpeas are still hard; allow for 24 hours.) When ready, drain chickpeas well and pat dry. DO NOT use canned chickpeas; the falafel mixture will fall apart.
Add chickpeas, herbs, onion, garlic and spices to the bowl of a large food processor. Run the food processor 40 seconds at a time until all is well combined and mixture is well ground but not pureed. Transfer the mixture to a container, cover and refrigerate for at least an hour or overnight until ready to cook.
Just before frying, add baking powder and sesame seeds to the falafel mixture and stir with a spoon. Use a falafel scoop or tablespoonfuls of falafel mixture and form into balls or patties. If mixture is too wet and not holding together, add flour a tablespoon at a time until the patties hold their shape.
Note: The original recipe did not use any flour as a binder; however, from my experience when I went to make the patties the next day the mixture was very wet and no where close to holding together. I ended up using upwards of 1/2 cup all-purpose flour to get them to hold their shape and they came out great. If you want to keep these gluten-free, I recommend having chickpea flour on hand.
Fill a medium saucepan with 3 inches of oil and heat on medium high until it bubbles softly or fill a deep fryer with oil and set to 375 degrees. Carefully drop the falafel balls until the oil and fry for 3 to 5 minutes until crispy and medium brown on the outside. Fry one test falafel first to make sure it holds together and to confirm the best fry time. Fry in batches and do not crowd the falafel in the fryer. Place cooked falafel on a paper-lined tray to drain.
Note: This recipe makes 40 to 45 falafel balls using a 4cm diameter by 2cm high falafel scoop. Fry falafel for 4 minutes at 375 degrees.
Serve falafel with tahini sauce as a part of a meze platter or as a sandwich or meal with pita, hummus, tzatziki, rice, tomato, cucumber and other small salads.
Falafel can be made ahead and frozen on a parchment-lined cookie sheet. Once they harden, transfer them to a freezer bag and store for up to a month. They can by fried directly from frozen.