In a large bowl, mix olive oil, lemon zest, lemon juice, crushed garlic, rosemary, oregano, Dijon mustard, salt, and pepper. Add the chicken thighs and rub the marinade into every piece. I like using my hands so nothing is missed. Let the chicken marinate for at least 30 minutes to absorb the flavors.
Heat a pan or grill over medium-high heat. Place the chicken skin-side down and cook until the skin is golden and crisp. This step locks in moisture and creates deep flavor. Flip once and let the other side cook briefly.
Transfer the chicken to an oven-safe dish. Add chopped shallots and pour in the chicken stock along with any remaining marinade. Bake until the chicken is fully cooked and tender, and the juices run clear.
While the chicken cooks, bring water or stock to a boil and cook the couscous according to package instructions. Once tender, drain well and fluff with a fork to keep it light and airy.
Stir fresh parsley into the couscous for color and freshness. Let the chicken rest for a few minutes before serving so the juices redistribute beautifully.