1 2-lb butternut squash, peeled, seeded, diced into 1/2-inch to 3/4-inch cubes, yielding about 6 cups of cubed squash (see how to cut and peel a butternut squash)
Olive oil
1 teaspoon butter
Salt
1 large yellow onion, chopped
2 teaspoons yellow curry powder
1 teaspoon whole mustard seeds (if you substitute ground mustard, only use 1/4 teaspoon)
A dash of ground cumin
1 Tbsp minced fresh ginger
4 cups chicken stock
1 teaspoon salt
1/2 cup sour cream (can substitute plain yogurt)
1/4 cup chopped fresh cilantro (can substitute parsley)