In a saucepan of boiling water cook the pumpkin until it is just tender; about 10 minutes.
Add 1 tablespoon of the olive oil to a frying pan over medium heat then add the onion and saute until translucent. Add the garlic, cumin and coriander. When it becomes fragrant and the pumpkin and stir through then set aside.
Place the couscous in a heatproof bowl then add the stock and leave to rest for 3 minutes.
Fluff the couscous the stir through the coriander. Add the flavoured onion and any residual onion and spices, gently toss then drizzle with the lemon juice and remaining olive oil, to taste.