Score each duck breast six to ten times. Season with salt and pepper and rub in the five-spice powder. Pour over a little olive oil and sprinkle on the thyme.
Preheat the oven to 200 C / Gas 6.
Place the duck breasts skin-side-down in a non-stick pan on a low to medium heat. Cook for six to eight minutes, or until the skin is golden brown and crispy, before pouring off any excess fat and flipping over the breast. Cook and seal the breast on this side for around 30 seconds before removing from the heat.
Turn the breast back onto the skin-side and place into the preheated oven for around 6 minutes for medium rare duck (see Gressingham’s website for timings on cooking duck). Remove the duck from the oven and leave to rest for five minutes.
Once cooked, place on a chopping board to rest – allowing the cooking juices to run over the board. In the meantime, chop the mint and chilli and add the lemon juice and a splash of oil. Mix together with the duck and cooking juices on the board. Slice the duck breasts, pouring over any remaining juices. Serve with a salad and some crusty bread to mop up the juices.