Combine chickpeas, 1 teaspoon (6g) baking soda, and 2 tablespoons (24g) salt in a large bowl. Cover with 6 cups (1.4L) cold water. Stir to dissolve salt and baking soda. Let stand at room temperature overnight. Drain and rinse chickpeas thoroughly.
Place chickpeas in a large Dutch oven or saucepan. Add remaining baking soda, 1 tablespoon (12g) salt, onion, celery, carrot, garlic, bay leaves, and rosemary, if using. Add 6 cups (1.4L) water and bring to a boil over high heat. Reduce to a simmer, cover with lid slightly cracked, and cook until chickpeas are completely tender and nearly falling apart, about 1 hour 30 minutes. Check on chickpeas occasionally and top up with more water if necessary; they should be completely submerged at all times. Let cool slightly.Combine chickpeas, 1 teaspoon (6g) baking soda, and 2 tablespoons (24g) salt in a large bowl. Cover with 6 cups (1.4L) cold water. Stir to dissolve salt and baking soda. Let stand at room temperature overnight. Drain and rinse chickpeas thoroughly. Discard onion, garlic, celery, carrot, bay leaves, and rosemary. Drain chickpeas, reserving their cooking water.
