Peel the shallots and chop finely and strip the leaves from the sage sprig and chop.
Peel and core 2 of the apples. Use the coarse side of a box grater to grate the apples.
Put the grated apple in a sieve and squeeze out the excess moisture.
Place the mince, sage, shallot, egg, salt, pepper and grated apple into a bowl.
Stir the ingredients together and divide the mixture into 4 even sized burgers.
Put a tablespoon of the oil in a pan over a medium heat.
Add the pork and apple burgers and cook for about 5 minutes.
Turn the burgers over and cook for a further 5 minutes.
Transfer the burgers to a plate and cover loosely with foil to rest.
Core the remaining apple and cut into slices.
Put the remaining oil in a griddle pan, if using, over a medium to high heat.
Add the apple slices and cook for a minute each side.
Serve the burgers in a bun with the apple slices.