Rub a bit of sea salt and pepper into each of the leg steaks.
Put the oil in the frying pan. Heat the pan up on a moderate heat and add the lamb, cook on both sides for about 6 minutes each side. Take care not to burn the outside of the meat.
Take out of the pan, place in a dish, cover with foil and leave to cool.
Bring a pot of salted water to the boil and boil the carrot and swede until soft, about 9 minutes.
While the carrot and swede is boiling, put 35g of the butter into the original pan and melt but don't burn. Add the sliced onions and cook until soft, bringing up any remnants of the meat from the pan.
Put the lamb into the oven, and switch it off.
To the onions, add the plain flour and mix, then add the stock, and bay leaves.
Mix well then add the redcurrant jelly, melt it down into the gravy, and leave to bubble gently for about 5 minutes.
Turn off the heat and leave to cool slightly.
Mash the swede and carrot, adding the remaining butter, salt and pepper and the fresh thyme; mix well.
Place on a plate with the meat and mash, then pour the gravy and onions over the lamb, and drizzle over the mash.