Bring water and quinoa to a boil in a saucepan. Reduce heat to medium-low, cover, and simmer until quinoa is tender and water has been absorbed, 15 to 20 minutes. Fluff quinoa with a fork and refrigerate until cold.

Combine chickpeas, carrot, celery, sunflower seeds, cabbage, and onion in a food processor and pulse until everything is roughly equal in size; transfer to a large bowl.

Stir quinoa, almonds, and raisins into the chickpea mixture; add mayonnaise, mustard, kelp flakes, relish, lemon juice, salt, and pepper. Stir the mixture until evenly seasoned.