1. Preheat the oven to 220C, gas mark 7. Toss the sweet potatoes with 1 tbsp oil, season and scatter on a parchment lined baking tray; roast near the top of the oven for 25 minutes, tossing halfway. Add the buns to the bottom of the oven for the last 5 minutes
2. Meanwhile mix the cranberry sauce and mayo; season and set aside. Mash the avocado and a squeeze of lemon juice; season and set aside. Toss the turkey breasts with the remaining 1 tbsp oil. Season and cook in a frying pan over a medium heat for 3-4 minutes on each side; set aside to rest. Add the bacon (or pancetta) and fry for 3-4 minutes, turning until crispy, then fry the sage leaves for 30 seconds or so until crispy.
3. To assemble, layer up rocket, turkey, cranberry mayo, smashed avocado, bacon and sage in the toasted buns and serve with sweet potato chips.