Mix all the marinade ingredients together and marinate the chicken thighs for a minimum 30 minutes. Leave aside about 1 Tbsp of the marinade for the vegetables.You could do this overnight too, if you like. Cover with a cling film and place in the fridge overnight.
Let's get Cooking
Turn the oven on to 200℃ (400℉/180℃ Fan).
Slice the onions into rings.Slice the capsicum into thick strips.
Place the chicken, onions, pepper strips and chillies into a baking tin that will hold everything comfortably.
Add the leftover marinade. Using your hands, mix everything together, covering the onions and pepper strips with the marinade.
Bake in the oven for 45 minutes.Baste after 30 minutes, and tuck the onions under the chicken to stop them from burning.
When done, leave to rest for 5 minutes, then serve with parsley if you like.