A simple dish where all the flavour comes from the butter mixture. The wholegrain mustard adds a kick to the turkey and the butter will help to keep the breast moist while roasting.
1. Preheat the oven to 200°C/gas mark 6.
2. In a small bowl, combine the butter with the garlic, tarragon, lemon zest and mustard.
3. Place the turkey on a chopping board, skin side down, and butterfly the breast to increase the surface area. Spread 2 tablespoons of the mustard and tarragon butter on the breast, then season generously with salt and pepper.
4. Turn over and carefully loosen the skin from the meat with your fingers. Gently push the remaining butter under the skin, then brush the skin with the oil and sprinkle with salt. Roll up the stuffed breast and secure it using 6 x 15cm pieces of butcher’s twine. Tie the pieces of twine around the breast at 4cm intervals, until the breast is holding its shape but isn’t rolled too tightly.
5. Put the carrots and onions in the base of a roasting tin to form a bed for the turkey. Place the turkey on top of the veg.
6. Cover with foil and roast in the oven for 20 minutes. Remove the foil and continue to roast, basting every 10 minutes, for a further 30 to 40 minutes, until the skin is golden and the juices run clear when tested with a skewer.
7. Allow to rest for 10 minutes before carving into slices.