Place the couscous in a large, heatproof bowl. Stir in the salt and the cinnamon. Pour the boiling stock over the couscous mixture, cover and let stand for 5 minutes. Remove cover, fluff couscous and allow to cool completely.
In a large bowl, combine olive oil, lemon juice and zest, red onion, cucumber, bell pepper, and green onions. Add the cooled couscous and toss until well blended. Stir in the cilantro leaves. Taste and adjust seasoning with salt and pepper.