Preheat the oven to 425°F (220°C).
In a large bowl, combine the olive oil, lemon juice, minced garlic, dried oregano, dried thyme, salt, and black pepper. Stir well to create the marinade.
Add the chicken thighs to the bowl and toss to coat evenly with the marinade.
Add the halved baby potatoes to the bowl and toss to coat with the remaining marinade.
Arrange the chicken thighs skin-side up on a large sheet pan.
Distribute the potatoes around the chicken on the sheet pan in a single layer.
Place the lemon slices evenly over the chicken and potatoes.
Roast in the preheated oven for 20 minutes.
After 20 minutes, add the trimmed green beans to the sheet pan, arranging them around the chicken and potatoes.
Return the sheet pan to the oven and roast for an additional 15 minutes, or until the chicken reaches an internal temperature of 165°F (74°C) and the potatoes are tender.
Remove the sheet pan from the oven and sprinkle the chopped fresh parsley over the chicken, potatoes, and green beans.
Serve immediately, spooning pan juices over the chicken and vegetables.