Chef Johns Falafel

Name: Chef John's Falafel
Ingredients: 1 cup dry garbanzo beans; 0.5 yellow onion, diced; 0.5 cup chopped fresh flat-leaf parsley; 4 cloves minced garlic; 1 tablespoon all-purpose flour, or more as needed; 2 teaspoons lemon juice; 1.5 teaspoons salt, or to taste; 1 teaspoon ground cumin; 0.5 teaspoon ground coriander; 0.25 teaspoon baking soda; 0.125 teaspoon cayenne pepper; oil for frying