Open up lamb loins on a work surface, sprinkle with thyme leaves and season to taste with sea salt and freshly ground black pepper, then re-roll and tie at 5cm intervals with kitchen string. Place lamb in a roasting pan with pumpkin, drizzle with olive oil, season to taste and cook at 200C for 20 minutes for medium rare, or until cooked to your liking, and pumpkin is tender. Remove and rest, covered loosely with foil for 10 minutes.
Meanwhile, cook couscous in boiling salted water for 7 minutes or until soft, drain, then add currants and cumin and cool slightly. Add anchovies, parsley, green onion, extra-virgin olive oil and vinegar, season to taste and stir to combine.
For yoghurt sauce place yoghurt in a small bowl, add mint and olive oil, season to taste, then stir to combine.
Slice lamb into 2cm-thick slices and serve over couscous with pumpkin wedges, drizzle with yoghurt sauce.
Note Mhammas is a lightly toasted Tunisian
couscous, larger than regular couscous but smaller than mograbieh
(pearl couscous) and is available from Simon
Essential Ingredient and other good delicatessens.