Mediterranean chicken skillet

For ➍
2 tbs olive oil
4 bone-in, skin-on chicken thighs
1¼ ts salt
1 ts black pepper
1 large red onion, cut into 1.5 cm slices
800 g cherry tomatoes
800 g fresh green beans, trimmed*
1 tbs finely chopped garlic
1 tbs drained & rinsed capers
1½ ts chopped fresh oregano, plus more for garnish
10 cl dry white wine

Preheat oven to 230°C. Heat 1 tbs of the oil in a large cast-iron skillet over medium-high. Sprinkle chicken on all sides with ¾ ts of the salt and ½ ts of the pepper. Place chicken in skillet, skin side down; cook, undisturbed, until brown and crispy, about 8 m. Flip, and continue to cook until browned on other side, about 4 m. Transfer chicken to a plate. (Chicken will not be cooked through.)
Place onion slices in skillet in a single layer over medium-high; cook, undisturbed, until slightly charred, 4 to 6 m. Flip, and cook until charred on other side, about 2 m. Transfer to plate with chicken.
Add tomatoes and remaining 1 tbs oil to skillet; cook, undisturbed, until blistered, about 4 m. Add green beans, garlic, capers, and oregano; cook until fragrant, about 1 m. Sprinkle with remaining ½ ts each salt and pepper. Stir in white wine. Place charred onions on top of tomato mixture; nestle chicken into tomato mixture.
Bake in preheated oven 12 to 15 m (probably more*).

Garnish with oregano before serving.

*It might be useful to pre-cook the green beans in water for 5 m.
**Or cook in skillet on stove-top for about 30-45 m.