If using dried corn, place in a large bowl and cover with lukewarm water by 1-inch. Soak for 18 to 24 hours. Drain well before using. In a large saucepan, cook the diced pork over medium-high heat until golden brown and the fat is rendered. Add the onions, celery salt, and cayenne, and cook until onions are soft, about 4 minutes. Add the garlic and bay leaf and cook, stirring, for 30 seconds. Add the potatoes and drained corn, and cook, stirring, for 1 minute. Add the stock and bring to a boil. Reduce the heat and simmer, stirring occasionally, until the potatoes are tender, 20 to 25 minutes. Add the milk and cream, and simmer for 5 minutes.

Remove from the heat and discard the bay leaf. Adjust the seasoning, to taste, with salt and freshly ground black pepper. Ladle into soup bowls and garnish each serving with the green onions.