Charmoula is a spicy Moroccan marinade that typically contains paprika, cumin, and garlic. The turmeric turns the couscous the color of the brilliant summer sun. For serving, spread the couscous on the plate in a sunburst.
In a high-sided frying pan or braiser, combine the wine, cilantro, and peppercorns. Bring to a boil, reduce the heat, and simmer. Add the chicken and poach, turning once, about 12 to 15 minutes. Season to taste with salt and pepper. Remove to a cutting board to rest.
Meanwhile, bring the stock to a boil. Add the couscous, stir, and bring to a second boil. Remove from the heat, cover, and let stand 5 minutes. Stir in the turmeric.
Combine the charmoula ingredients in a small bowl. Cut the chicken breasts in half. Divide the couscous among 4 dinner plates and arrange chicken breasts on top. Serve each with 1/4 cup of the charmoula.