Turn the oven to 190°C. Put the potatoes in a pan of water, bring to the boil on the stove and cook for about 8 minutes.
While they're parboiling, prepare the sauce by combining the honey, mustard, garlic and oil in a mixing bowl. Season to taste.
Cut the tenderloin into two pieces and put in a smallish roasting pan surrounded by the drained potatoes. Cover the fillets all over with the sauce then sprinkle the sage onto them. Roast in the oven for 35 minutes.
Plate up the fillets & potatoes and keep warm. Add about 40 ml of wine to the pan and stir over a low flame to create a simple jus. Pour this over the pork and potatoes to serve. Broccoli & baby carrots are a good accompaniment.