In a large pot bring 4 to 5 cups of salted water to a boil and add in the cubed butternut squash. While the squash boils, sauté carrots first for a few minutes then add in the onion. Incorporate well and let the vegetables sweat for another 5-7 minutes.
Mix in the garlic and after about a minute or two lower the heat, add in all the spices and fresh ginger. Allow the vegetable mixture to become fragrant.
Check on the squash and lightly press one piece against the walls of the pot with a wooden spoon, if the squash is easily smashed add in the sautéed vegetables. Reduce heat to medium-low and let all the ingredients lightly boil together for another 7-10 minutes to incorporate the flavor. Add in the vinegar.
You can blend the soup with an immersion blender right in the pot or transfer into a blender. Plate soup bowls and spoon a small dollop of quark, followed by pine nuts, sage leaves, and sumac.
As an option, you can sprinkle additional vinegar for optimum flavor. This soup is even better on day 2 and 3!