In a saucepan, heat the butter and sauté the onions and celery until tender.
Add oyster water, half-and-half, and peppercorns. Bring to a very light simmer and cook slowly for fifteen minutes.
Add oysters and green onions, and cook for another three to five minutes, until the oysters are plumped up and the edges are curly. Add salt to taste (you may not need any, depending on the saltiness of the oysters and oyster water).
