Fry the onion in the oil until translucent. Add the rest of the ingredients and simmer slowly for 20 minutes. Stir constantly.
Finally, squeeze the lemon juice into the sauce and season to taste with salt and pepper, set aside.
For the Lamb:
Preheat the oven to 140 ° C.
Cut the skin and fat off the leg of the lamb.
Brush well with olive oil and garlic, season with salt and pepper spread a layer of apricot sauce over.
Place in an ovenproof dish with a tight-fitting lid or place the meat in aluminium foil, THEN IN THE OVEN TRAY, it works well, and bake for about 3 to 4 hours.
Remove from the oven and pour off the sauce and add to the apricot sauce. Cook for a few minutes. Season to taste. set aside but keep it warm.
Place meat uncovered back in the oven and bake the leg golden brown, let rest for a few minutes, cut, and serve with the sauce.