Pat thighs dry with paper towel. In a shallow dish, combine the lemon juice, 2 tablespoon of olive oil, vinegar, garlic, basil, oregano, parsley and salt. Pour out half of the marinade and store in a jug to use later.
Add the chicken to the marinade in the dish and coat evenly. Cover and marinate for 15 minutes if rushed; 1 hour if time allows; or over night, turning each chicken thigh occasionally in the marinade.
Preheat oven to 220°C | 430°F. Heat the remaining 1 tablespoon of olive oil in a large oven-proof pan or skillet over medium-high heat. Sear the chicken on both sides until golden browned (about 4 minutes each side). Drain some of the excess fat, leaving about a tablespoon for added flavour.
Arrange the vegetables around each chicken thigh. Drizzle the vegetables with the remaining marinade, tossing them through the oil mixture to evenly coat.
Cover skillet or dish with lid (or foil), and bake until the potatoes are soft and the chicken is completely cooked through (about 35 minutes). Change oven setting to grill / broil on a medium heat setting; uncover and cook for about 5-10 minutes, or until chicken and potatoes are crispy and golden browned. Serve with olives and lemon slices.