Roasting lamb method
Cut potatoes so they can be used as a trivet for the lamb and place in the roasting tray.
Rub a small amount of cold-pressed rapeseed oil over the lamb and season with salt and pepper.
Place the lamb on the potato trivet.
Slice the onion thinly and place in the roasting pan.
Dissolve the lamb stock cube into 500ml of hot water and pour into the roasting tray.
Place a sprig of fresh thyme in the lamb stock in the roasting tray.
Roast the lamb at 190c until the core temperature is how you like it: medium rare: 54c / medium: 60c / medium well: 66c / well done: 72c.
When the core temperature is reached, take the lamb out of the oven and let it rest somewhere warm for 45 minutes before carving.
Parmentier potatoes method
Wash and peel the potatoes and cut into large dice (1 inch x 1 inch cubes)
Place in salted boiling water in a saucepan, turn the heat down to a simmer and set a timer for 6 minutes.
Drain the potatoes but keep the potato water in case you need it for the beef gravy.
Let the steam drive off the potatoes and put them in a lightweight plastic bowl.
Add a little cold-pressed oil and gently toss the potatoes so they are evenly coated with the oil.
Sprinkle the finely chopped rosemary over the potatoes and gently toss them again so the rosemary evenly coats the potatoes.
Roast in a preheated roasting tray in the oven at 190c until they are golden and crispy on the outside and fluffy on the inside (you will need to turn them once during the cook). They will usually take around 30 - 45 minutes.
Lamb gravy method
When the lamb comes out of the oven set it aside on a warm plate to rest somewhere warm.
Put the roasting tray with the lamb stock, lamb juices, potato and onion directly on the hob and set a low temperature.
Bring the temperature of the roasting tray up until the stock starts to bubble then add the flour and keep whisking for at least two minutes to cook out the flour.
Add the red wine and keep whisking until the gravy starts to bubble again.
Cook out for a few minutes and adjust the gravy consistency to your taste.
If it's too thick add some of the reserved potato water and if it's too thin add a little cornflour mixed with a little water.
If you like you can add a bit of salted butter to the gravy and whisk it in just before serving.
You can keep the gravy warm on a low setting on the hob or put it in a jug for pouring.
You can also place the sliced lamb in the gravy on a low setting on the hob if you need to keep it warm.
Green beans method
Put the green beans in a saucepan of salted boiling water for 1 - 2 minutes then immediately drain them and place them in a separate bowl.
Wwarm the oil, butter and grated garlic in a frying pan on a very low heat.
2 minutes before serving turn the heat up to medium/high until the butter starts to foam then immediately add the blanched green beans.
Let them warm up for 30 seconds then toss them so all sides are coated evenly in the oil, butter and garlic.
Cook them for a minute or so until they are nice and hot then serve immediately.