Place the chickpeas and baking soda in a large bowl and cover them with plenty of water (the chickpeas should be covered by approx. 6 cm / 2–3 inches of water). Let them soak overnight.
The next day, drain the chickpeas in a colander.
Peel the onions and garlic, then roughly chop them (this makes it easier for the food processor to blend them later).
Add the remaining ingredients for the falafel mixture and the spices to the soaked chickpeas (except the sesame seeds) and blend everything in a food processor.
Scrape down the sides of the bowl and blend again. Repeat this step 2–3 times until the mixture has an even consistency and holds together well (but is not mushy).
Transfer the mixture to a large bowl and mix in the sesame seeds.
Cover the bowl with plastic wrap and refrigerate for approx. 40–60 minutes.
Meanwhile, prepare the sumac onions and tahini sauce. I’ve linked the recipe for my tahini sauce earlier in the blog post.
For the sumac onions, mix the sumac, onions, and olive oil well in a bowl.
Pour the oil into a pot (approx. 2–3 cm / 1 inch deep) and heat it until bubbles form around the handle of a wooden spoon dipped into the oil (approx. 190°C / 375°F).
Remove the mixture from the refrigerator and shape it into balls using a heaping tablespoon of the mixture. Carefully place the falafel into the hot oil (or use a falafel maker).
Repeat this step until the bottom of the pot is well covered.
Fry for about 1 minute without moving the falafel, then turn them and fry for another 1–2 minutes until crispy.
Remove them from the pot and let them drain on a paper towel.
Serve with hummus, fresh salad, sumac onions, tahini sauce, and pita bread.