Break up sausage meat and sauté in a frying pan over low heat until lightly browned; drain, reserving fat.
Place sausage meat in a large mixing bowl.
Return 2 tablespoons of sausage fat to the frying pan (if sausage meat didn't render enough fat, substitute olive oil); sauté onions until golden- about 8 minutes; add optional minced liver and sauté with onion an additional 2 minutes.
Add onion mixture to sausage.
Sauté mushrooms in 2 additional tablespoons of sausage fat (or olive oil) until pieces begin to separate from each other; add to sausage mixture.
Add olives, anchovies, capers, orange zest, eggs, garlic, and herbs to sausage meat.
Fold in the croutons, add salt and pepper to taste.
Loosely stuff front and rear cavities of turkey immediately before roasting, or bake for 50 minutes in a 350 degree F.
oven in a covered casserole.
Makes about 2-1/2 quarts, or enough to stuff a 16- to 20-pound turkey.