Roast beef sirloin
For the beef, season the whole sirloin and seal in a pan in light olive oil for 4-5 minutes, turning to sear all sides.
Place on a roasting tray and put in the oven at 170C for about 30 minutes, depending on weight. Pop the carrots around the beef to roast. Remove beef from oven and leave to rest for at least 10 minutes.
Champ potato cake
While the meat is cooking, peel the potatoes and boil in salted water for about 15 minutes, until tender. Drain and crush with butter, the sliced scallions (spring onions), seasoning and a pinch of flour. Make into patties, dust in flour and fry off in pan in a little butter.
Sauces
For the mustard sauce, melt a little more butter in a pan. Stir in a couple of teaspoons of English and Dijon mustard and a little water. Add pinch of turmeric and whisk. Set aside.
For the red wine sauce, when you have removed the sirloin from the roasting tray tip out a little fat then heat the rest in the tray on the hob. Add the chopped shallot and cook until softened, then deglaze the pan with the port and
wine. Bring to the boil and add the stock. Add a teaspoon of gravy granules and reduce down, stirring.
Serve
Serve the beef with the red wine sauce, and the potato cakes and watercress alongside. Drizzle the vibrant mustard sauce around.