Place the chicken thighs in a bowl and rub salt, pepper, oregano and black vinegar over them and let marinate for 30 minutes.
Mix the herbs with walnuts in a blender and chop until fine. Zest the orange and squeeze half of the juice.
Heat pan with a little oil and sear the chicken thighs on both sides until brown then place on baking tray. Bake in oven at 180 degrees C for about 25 minutes or until cooked.
Just before taking the chicken out of oven make the herb sauce. Saute the minced garlic in olive oil until fragrant. Then add the chopped herbs and stir. Add a little water and sour cream. Season with salt, pepper, orange zest and orange juice to brighten up the flavour.
Pour the herb sauce over the chicken before serving.