Soak chickpeas in a large bowl with water (cover by 3–4 inches) for 24 hours, adding more water as needed. They should break apart easily when ready.
Preheat oven to 375°F and line a baking sheet with parchment or a silicone mat.
Drain chickpeas and add to a food processor with garlic, onion, cumin, cayenne, cilantro, 1 teaspoon salt, pepper, baking soda, and lemon juice. Pulse until minced but not puréed. Add water only if needed to blend; keep the mixture as dry as possible. Adjust seasoning to taste.
Scoop into 20 balls (about 1½–2 inches), flatten into patties, and press both sides into sesame seeds. Place on baking sheet and mist both sides with cooking spray.
Bake 10–12 minutes per side, until golden. Serve hot or at room temperature with tahini sauce.