For the turkey
For the buckwheat salad
For the stuffing, place a medium frying pan over a medium high heat. Drizzle with oil and sauté the leeks for 5 minutes or until soft. Place in a large mixing bowl.
Add the sultanas, pumpkin seeds, mashed pumpkin, lemon zest, sage leaves and breadcrumbs. Mix well and season with the salt and pepper.
For the turkey, generously grease a large roasting tin with oil.
Place the turkey breast on a board and gently remove the skin. Turn over and cut horizontally almost all the way through the thickest part of the breast and open up like a book, so that the turkey has a flatter, more oblong shape. Cover with a sheet of cling film and bash with a rolling pin until around 2.5cm thick all over.
Place a sheet of cling film on a work surface and put eight pieces of kitchen string, each 50cm long, roughly 4cm apart along its length.
Place the flattened turkey breast, smooth-side down, on top of the strings and arrange the filling all the way down its length. Bring up the cling film to enclose the filling and roll into a sausage shape. Secure the ends tightly and tie the string to secure the breast roll.
Bring a large pot of water to a gentle simmer and place the breast roll in the water. Poach for 10 minutes then remove and allow to cool. Remove the cling film.
Heat a pan over a medium heat with a little olive oil and fry the roll for 2-5 minutes, turning often until golden on all sides. Allow to rest for 10 minutes before slicing.
To make the buckwheat salad, place the buckwheat and water in a saucepan with the salt and bring to a boil. Cook for 15 minutes or until tender.
Drain and add the rest of the ingredients, seasoning well.
Slice the turkey breast into 1cm thick slices and serve on top of the buckwheat.