For the dressing , stir all the ingredients in a glass bowl until smooth.

For the potatoes, Preheat the oven to 200C/180C Fan/Gas 6. Put the potatoes into a pan and just cover with water. Add a tablespoon of salt, cover with a lid, and bring to the boil. Boil for 15 minutes, until cooked (they will slide off when pierced with a knife). Drain thoroughly in a colander, then set the colander on top of the cooking pan and cover the potatoes with a tea towel. Set aside for 10 minutes to steam dry. Put the olive oil, into a roasting tin. Tip the potoatoes and gently toss them around in the olive oil . 

Put the tin into the oven and roast for 20 minutes. At this point give the potatoes a turn and then return them to the oven for a further 20-30 minutes or until golden and crunchy. Season the potatoes with salt and pepper and set aside.

Brush the turkey breast with some of the dressing and place it in a roasting tray covered with aluminium foil. Cook in the centre of the oven on high heat for 25-30 minutes until it's cooked through.

To serve , place the sliced turkey breast over the rocket leaves. Add tomatoes, avocado and potatoes. Drizzle the dressing or serve dressing on the side.