1. Heat oil in a large saucepan over moderate heat until hot but not smoking. Add neck and giblets; cook, turning occasionally, until golden brown, about 3 minutes. Add vegetables and cook, stirring occasionally, until golden, about 5 minutes. Add broth, rosemary, and 4 cups water; simmer, uncovered, until liquid is reduced to 5 cups, about 20 minutes.
2. Pour stock through a sieve into a bowl (discard solids). Makes 5 cups.