Note 1: For reference, generally, 1 cup of dried couscous will give you about 2.5 cups of cooked couscous.
Note 2: If using jarred peppers, use just half a pepper instead of one, as the roasted pepper jars generally have some vinegar, and the flavor of the roasted pepper can be overpowering due to the vinegar.
Note 3: Recipe timings. The tzatziki recipe takes 15 minutes to make. The instant/5-minute couscous takes 5 minutes to make. And the chicken takes just 10 minutes to cook (plus 30 minutes marinating). Ideally, make the tzatziki and marinade the chicken ahead of time. If making everything at the same time, use this order: 1) put the chicken in the yogurt marinade and set it aside 2) make the tzatziki 3) prep all the other ingredients, like halving the baby tomatoes and crumbling the feta, 4) make the couscous and cook the chicken at the same time.