For the pork, heat the oil in a frying pan. Add the pork and cook for five minutes on each side, until cooked through.
For the creamed leeks, melt the butter in a hot pan. Add the leeks and chard and sauté for three minutes.
Add the double cream and sage, warm through and season to taste with salt and freshly ground black pepper.
To serve, place the creamed leeks onto the centre of a warmed plate and top with the pork. Arrange the new potatoes around the plate.