1) Heat the oven to 190C/Gas 5.
2) Place the pine nuts on a sheet pan and toast until golden, 3 to 5 mins. Set aside and leave oven on.
3) Bring beef stock to a simmer in a small saucepan. Add the butter and stir in the couscous. Cover the pot and remove from the heat. Let sit for 5 to 10 mins. Fluff the couscous with a fork and place into a medium bowl. Stir in the toasted pine nuts, lemon zest and juice, tomatoes, 1 tbsp of the chopped mint, chorizo, feta cheese and all but 3 tbsp of the cucumber. Add salt and pepper to taste. Cover and set aside to cool.
4) Butterfly the loin, lay in the couscous stuffing and tie with butcher twine.
5) In a small bowl combine the cumin, olive oil, salt and pepper, to taste. Brush all sides of the lamb loin with the flavored oil.
6) Heat a saute pan big enough to hold the loin, brush with oil. Place the loin in the pan and cook, turning until seared on all sides, about 2 mins per side. Transfer to a sheet pan to finish cooking in the oven, about 5 mins.
7) Meanwhile, in a small stainless bowl, mix the yoghurt with the remaining mint and cucumber. To serve, slice couscous lamb loin and place on toasted crostini. Garnish with yoghurt sauce and fresh mint.
A viewer, who may not be a professional cook, provided this recipe. The Food Network Kitchens chefs have not tested this recipe and therefore, we cannot make representation as to the results.