Preheat the oven to 190 °C.
Combine together soy sauce, orange juice, ground garlic, crushed black pepper, cayenne pepper, and 1 TBSP olive oil. Pour over the chicken thighs and let sit until you prepare the potatoes.
Cut potatoes in 2 cm chunks and drizzle with 1 TBSP olive oil and add salt to taste. Mix well.
Place potatoes in a baking tray and add chicken thighs skin side up. Add orange slices and thyme springs.
Roast in the preheated oven for 50 minutes.