For the lamb, grind the coriander seeds, cumin seeds, cinnamon and black peppercorns in a mortar with a pestle. Rub the spice mixture over both sides of the lamb.
Heat a griddle pan until hot and drizzle the olive oil over the lamb. Cook the lamb for 4-5 minutes on both sides (for medium), or until golden-brown and cooked to your liking. Remove from the pan to rest on a warm plate.
Return the pan used to cook the lamb over a low heat and and stir in the honey and pomegranate seeds, scraping up any browned bits from the bottom of the pan with a wooden spoon. Cook until the honey begins to bubble, then remove from the heat.
For the couscous 'cake', melt the butter in a small frying pan until foaming. Mix the cooked couscous with the basil, mint and flatleaf parsley. Pack the mixture into the pan and fry over a low heat for 5-7 minutes on each side (turn the 'cake' over carefully), or until golden-brown and crisp.
To serve, turn the couscous 'cake' out onto a plate. Thickly slice the lamb and arrange over the couscous. Drizzle the pomegranate and honey sauce around the edges of the plate.
