Cumin-Spiced Butternut Potato Soup

I hosted friends for dinner the other night, something by now you know I love to do.  One of the families who came had intended to host, but when that didn't work out, I offered my home. They agreed, but only if they could bring dinner.  That was not easy for me to agree to, but I did. And how glad am I? They brought me this wonderful soup! The original recipe was from my friend, Larry's cousin, but my friend, Robyn, adapted it to make it vegan. She is not a vegan herself, but how awesome of her to do this for me?

For 4 servings (roughly):
Ingredients:
1 Large Butternut - Peeled and chopped
2 Medium Size Russet Potatoes - Peeled and chopped
1 Large Carrot - Chopped
1 Large Celery - Chopped
1 Medium Brown Onion - Chopped
Vegetable Stock
1 TBSP Ground Cumin
Salt and Pepper
3 TBSP Olive Oil
Non-Dairy Sour Cream
Bunch of Scallions - ChoppedPumpkin Seeds 
Directions:
Use a 5 quart pot and put on medium heat.  Add olive oil.  Once heated, add butternut squash, potatoes, carrot, celery and onion until they start to brown (5 - 8 minutes). Season with salt and pepper. Make sure to stir the vegetables so they don't stick to the bottom of the pot.
Once vegetables start to brown, pour in enough vegetable stock until it covers the
vegetables.  Turn heat to high and bring stock to a boil.  Then cover pot, turn heat down and simmer for one hour. Stir occasionally.
After an hour, and once the vegetables are extremely soft, puree soup in pot
with an electric hand blender.  Stir in cumin and salt and pepper.
Serve hot with a dollop of vegan sour cream, some chopped scallion or some pumpkin seeds.