Bring the stock to the boil in a pan, add the carrots, reduce the heat, simmer for approx. 5 mins. and remove from the hob. Add the couscous and spinach, mix with a fork, cover and leave to absorb for approx. 5 mins. Add the mint, mix with a fork, season.
Combine the oil with the garlic, season. Add the fillets, mix. Heat a wide-bottomed non-stick frying pan, fry the fillets for approx. 2 mins each side and arrange on the spring couscous.