- Preheat the oven to 400°. 
- Combine the bread, chopped parsley, lemon peel, sage, 1 tablespoon of salt and the pepper in a large deep bowl and toss with a spoon until well mixed. 
- In a heavy 10- to 12-inch skillet, melt the butter bits over moderate heat. When the foam begins to subside, add the chopped onions. Stirring frequently, cook for about 5 minutes until they are soft and translucent but not brown. 
- Stir in the celery and cook for a minute or so; then, with a rubber spatula, scrape the entire contents of the skillet into the bread mixture. 
- Add the oysters and egg and stir the ingredients gently but thoroughly together. Taste the oyster stuffing for seasoning. 
- Bake until hot throughout and crusty on top.