1Use knife to cut corn off of the cobs and set aside. Place cobs into 5 to 7 quart pot and cover with 6 cups of cold water. Bring to a simmer for 30 minutes and cool. Strain the cobs and discard them, reserving the water which is now your corn broth.
2Return the pot to the stove over medium-low heat. Add the butter and let it melt, then add the oil. Add the onion, celery, salt and remaining Tbls of water. cook, stirring until the veggies are soft and translucent, six to eight minutes.
3Stir in the thyme and chopped garlic; cook for an additional minute. Increase the heat to medium-high and add the wine. Bring to a simmer and cook, stirring continuously until it is reduced in volume (I did not do this and the soup tasted just as good). Add the cream and sweet potatoes. Bring to a simmer and cook for 20 to 30 minutes, or until the potatoes are tender. Add the corn kernels and simmer until just cooked, about 5 minutes.
4Add the white vinegar, a couple of grinds of black pepper, and parsley. Season to taste with Kosher salt.