Preheat the oven to gas 7 / 210C / 425F
Mix the olive oil, chopped rosemary, 2 of the garlic cloves and the smoked paprika together and season well with salt and pepper, around 1/2 tsp low-sodium salt and 1/2 tsp black pepper. Prick the lamb all over with a knife then rub the mix over the whole surface
Put the onions, remaining whole garlic, stock and wine into a roasting tin, put a wire rack on top then put the lamb on top of the rack. Roast uncovered in the oven for 30 minutes
This browns the meat. Now reduce the oven temp to gas 3 / 160C / 275F
Cover the tray loosley with foil
Roast 35 minutes per pound for rare, 40 minutes per pound for medium and 45 minutes per pound for well done
Let the lamb rest covered in the foil and with a clean tea towel draped over to keep it warm for 30 minutes. The meat will absorb some of it's juices back and the stock will be full of flavour having caught the drippings
Transfer the lamb to a cutting board. Pour / spoon off the fat from the roasting tin and discard. Sieve the roasting juices and softened onion into a measuring jug. Press down to get all the flavour from the garlic and onion juices into the stock. Add boiling water to the jug if needed to make it up to 570ml
Bring to boil in a saucepan, adding the redcurrant jelly to dissolve. Mix the cornflour with a couple of tablespoons of cold water then add to the pan and whisk until thickened and smooth.
Add some salt and pepper to taste
Slice the lamb thickly and serve with seasonal vegetables and the gravy
