Use a small sharp knife to score the skin of the duck. Pat the skin with a paper towel and generously season with salt. Place the duck skin-side down on a cold cast iron pan and then bring it to a medium heat to allow the fat to render. Leave on heat for 5 minutes.
Turn duck skin-side up and then place pan in the oven to finish cooking for 5-7minutes. Remove duck from the oven and allow to rest for 10 minutes.
To prepare the salad, oil a griddle pan and grill the peach slices on the pan for 1 minute on each side. In a large salad bowl toss the rocket, peaches, pecans and feta. Add the honey, mustard and olive oil to a jar with an airtight lid and shake to emulsify. Drizzle over salad and serve alongside duck.