Chop the onion into slices and sauté until it caramelizes.
Chop the pumpkin and the sweet potato into 2 cm pieces and add them to the pot. Saute
Add the garlic, ginger, orange zest, orange juice, 1 tablespoon cardamom, salt, and pepper.
Add the 900 gr of water and lower heat.
Simmer for 25 minutes, until the vegetables soften. Stirring occasionally with a wooden spoon.
Remove from heat and beat for 4 minutes with an immersion blender until the soup becomes completely smooth and creamy. If it is too thick you can add a little bit of water and stir.
Serve the soup in bowls. You can add caramelized onions, crouton and ground cardamom.