Place the cous cous, stock and cumin (if using) in a large heat-proof bowl. Stir, cover with cling film and leave for 10 minutes, until all the water has been absorbed. Remove the cling film and fluff up the couscous with a fork.
While the couscous is soaking, heat a small non-stick frying pan over a high heat. Add the pine nuts and cook for 1 minute, constantly moving them, until they are brown.
Drain the oil from one of the cans of sardines and drizzle into the couscous. Add the onion, carrots, tomatoes, chick peas and coriander, season with black pepper, and gently mix everything together. Divide between 4 plates or bowls.
Drain the remaining can of sardines and discard the oil. Top each plate of couscous with the sardines and pine nuts. Grind over some black pepper and serve.