Heat a large heavy-bottomed pot with a lid over medium-high heat.
Add the olive oil, onion, celery, potatoes, and butternut squash to the pot. Cover and reduce heat to low, sweat the ingredients at a low sizzle for 15-minutes, shaking the pot occasionally.
Increase the heat to medium-high, clear space in the bottom of the pot, and add the garlic and ginger. let saute for 1-minute.
Set the fresh sage aside. Add the stock, lemon, and dry seasonings, then bring to a boil. Reduce heat to low, cover, and simmer approximately 20-25 minutes.
Once the potatoes and butternut squash are soft, remove from the heat and add the fresh sage leaves.
Working in small batches, puree the soup in the blender. Be careful using a blender with hot liquids, hold the lid down hot a pot-holder to avoid any accidents.
Serve hot, garnished with fresh sage leaves, and if you like, toasted bread.