Heat the oven to 120 C. Place the rhubarb into a shallow baking dish and drizzle with honey, cordial and scatter over the sugar and star anise. Cover the dish loosely with pieces of greaseproof paper and place in the oven for 20 minutes, or until the rhubarb is soft but not broken down. Remove from the oven and set aside.
Season the venison all over with salt and pepper and rapeseed oil. Heat a pan over a high heat and once really hot add the venison loin. Cook, for 4-5 minutes for medium-rare. Remove the meat from the pan and leave to rest somewhere warm for 3-4 minutes.
Divide the rhubarb equally between 4 large plates, reserving the syrup in the bottom of the plate. Cut the loin into thick slices and lay it around the rhubarb, scatter over the chard and drizzle the reserved honey-and-anise syrup. Serve straight away.