Melt the butter in a large saucepan over medium-high heat. Add the sage leaves and leeks and let them cook for 6-8 minutes, stirring ocassionally.
In a small bowl, whisk the flour together with 1/4 cup of vegetable stock. The add the flour mixture, the remaining vegetable stock, pumpkin, salt, and pepper to the pot.
Bring the soup to a boil, then reduce the heat and let the soup simmer for 5 minutes. Stir the soup ocassionally so the pumpkin doesn’t stick to the bottom of the pot.
Blend the ingredients together in a heat-proof blender or with an imerssion blender. Tip with fresh chives and serve.
Notes
Recommended low FODMAP serving – 3/4 cup per sitting.