Stir together the lemon juice, garlic, herbs, red pepper flakes and olive oil in a bowl. Place the chicken in a large zip lock bag and pour 3/4th of the marinade on top. Marinate in the fridge for 12- 24 hours.
Once the chicken is marinated, preheat oven to 375 degrees F.
Place the potatoes in a large bowl and drizzle with the remaining marinade, toss to combine. Season the potatoes with salt and pepper. Arrange the potatoes on the bottom of a large cast iron skillet. Remove the chicken from the marinade and place on top of the potatoes and season the chicken with salt and pepper.
Roast the chicken and potatoes in the oven for 1 hour 15 minutes until golden and crispy.
Top with the chopped cucumbers, cherry tomatoes and feta and serve immediately.