Preheat the oven to 180°C
Warm half the oil in a large frying pan over medium heat. Add onion and cook whilst stirring for 2 minutes or until translucent. Transfer to a small bowl with almonds, prunes, oregano, breadcrumbs and egg. Season with salt and pepper. Mix to combine. Wipe pan clean.
Lay turkey breast opened out, skin side down between two sheets of baking paper. Use a meat mallet to flatten turkey to a rough rectangular shape of even thickness all over - about 2-3cm thick. Remove and discard the top sheet of baking paper. Spread almond mixture over one of the long edges and roll turkey tightly from that side to enclose filling in a log shape. Use kitchen string to truss and tie the turkey securely.
Warm the remaining oil in the same large frying pan as above over high heat. Add the turkey and cook for 5 minutes, turning to brown all sides evenly. Transfer turkey to a roasting dish and roast for 30 minutes or until cooked through.
Rest turkey and slice to serve.