Preheat the oven to 180°C (160° fan-forced). Line 1 roasting pan and 1 large, flat baking tray with baking paper.
In a small bowl combine half the oil, oregano, lemon juice, olives and half the garlic. Using a small, sharp knife make incisions over top of lamb. Place lamb on lightly oiled metal rack set over prepared roasting pan, spoon over marinade and season lamb. Cover with foil and roast in oven for 1 hour.
Meanwhile place remaining oil, remaining garlic, thyme and potatoes in a large bowl. Season and toss to coat. Lay potatoes on prepared baking tray, slightly overlapping. Place potatoes in oven, remove foil from lamb and cook lamb and potatoes for a further 40-45 minutes, turning potatoes halfway, or until lamb is cooked to your liking and potatoes are golden. Remove lamb from rack and set aside on a tray loosely covered in foil for 15 minutes to rest.
Meanwhile, spray a large frying pan with oil. Heat over medium-high heat, add broccolini and asparagus and cook for 2-3 minutes. Add lemon zest, chilli and baby capers and cook for a further minute.
Slice lamb and serve with potatoes, greens, lemon wedges and extra oregano.
For a full leg of lamb double the ingredients for this recipe. Cooking time for lamb will need to be adjusted accordingly depending on weight.
A butterflied or boneless leg of lamb or rolled lamb loin would also work well in this recipe – depending on weight cooking time will be reduced (due to lack of bone).
Capers can be swapped for olives, if preferred; lemons can be swapped for limes; any greens (e.g. beans, zucchini, snow peas, spinach, broccoli) can be used in this recipe.