Place the dried chickpeas in a large bowl and cover with plenty of cold water. Let them soak overnight or for at least 12 hours. Drain and rinse well before using. Do not cook the chickpeas.
Add the soaked chickpeas, onion, garlic, parsley, cilantro, cumin, coriander, baking soda, salt, pepper, and lemon juice to a food processor. Pulse until the mixture resembles coarse crumbs and holds together when pressed.
Mix in the chickpea flour. If the mixture feels too wet to shape, add another tablespoon of flour until it holds together easily.
Cover and refrigerate the mixture for 30 minutes to help it firm up.
Using a cookie scoop or tablespoon, shape the mixture into balls or small patties.
Heat about 3 inches of oil in a deep pot to 350°F (175°C).
Carefully fry the falafel in small batches for 3 to 4 minutes, turning occasionally, until they are deep golden brown and crisp on all sides.
Transfer the cooked falafel to a paper towel-lined plate or wire rack to drain any excess oil.
Serve immediately with warm pita, tahini sauce, hummus, fresh vegetables, or over a salad.