Cut the squash into large wedges, place on a baking tray and put into the oven at 160c/ Gas mark 3 cooking until soft. Remove from the oven and leave to cool slightly before removing the seeds.
Place the oil in a large stock pot over a medium heat. Once hot, add the onions, 1tsp of salt and the lemon zest, sauté for around five minutes, or until softening
Add the squash and carrots to the onions and stir well, add a good pinch of salt and saute for a couple of minutes.
Add the bay leaves, ground ginger and turmeric, stir well and then add enough water to cover.
Boil until all the vegetables are soft.
Blend the soup with a hand blender and adjust the seasoning using the pepper and a touch of salt, if needed.
For the gremolata: Place the parsley, lemon juice, garlic and oil in your processor and blitz until smooth.
Place the pumpkin seeds in a frying pan and toast over a high heat until coloured and splitting.
Add the pumpkin seeds to the blitzed parsley mix and pulse a few times to break them down and season to taste. Add a spoonful on top of the soup at the point of service.