Preheat the oven to 200 °C (conventional oven)/ 180°C fan-forced (400° Fahrenheit/Gas 6). Line a baking tray with non-stick baking paper.
Place the pumpkin (squash), sweet potato and zucchini in a baking dish and drizzle over half of the olive oil. Add the garlic, rosemary and salt and pepper to taste, then toss with your hands to coat evenly. Cook for 20 minutes or until the vegetables are tender and golden. Set aside to cool slightly before adding to the couscous. Discard the rosemary and garlic.
Meanwhile, preheat a barbecue grill or large frying pan on medium-high heat. Brush the lamb backstraps with the remaining olive oil and turn to coat. Cook the lamb for 2 to 3 minutes on each side for medium or until cooked to your liking. Transfer the meat to a plate and cover loosely with aluminium foil.
To make the roast vegetable couscous, bring the vegetable stock to the boil and stir into the couscous. Cover for 5 minutes or until stock is absorbed. Using a fork, fluff the couscous. Season to taste, then add an extra tablespoon of extra virgin olive oil. Add half of the parsley and mint to the couscous. Stir in the roasted vegetables to combine.
Place the remaining parsley and mint on a plate. Roll the rested lamb into the herb mixture to coat. Thickly slice the lamb and drizzle extra olive oil on top. Serve with roast vegetable couscous and lemon wedges – buon appetito.
3 lamb backstraps (approximately 200g each)|250g jab or butternut pumpkin (squash), peeled, seeded, cut into 2cm cubes|1 medium-sized sweet potato, peeled, cut into 2cm cubes|1 medium-sized zucchini, cut into 2cm cubes|4 tablespoons (80ml) extra virgin olive oil, plus extra to serve couscous|2 garlic cloves, halved horizontally|2 sprigs rosemary, roughly chopped|200g couscous|250ml vegetable stock|4 tablespoons finely chopped flat-leaf parsley|4 tablespoons finely chopped mint|4 lemon wedges|Sea salt, freshly ground black pepper