Start with the marinade. Whisk together lemon juice, zest, Dijon mustard, garlic, oregano, thyme, salt, pepper, and olive oil in a bowl. Place the chicken thighs in a large glass dish or zip-top bag, pour the marinade over them, and turn to coat. Cover and let it chill in the fridge for at least 30 minutes—but if you’ve got time, aim for a couple of hours or even overnight. Trust me, the longer the better. The marinade is where all that flavor magic begins.