Wash and peel the large field mushrooms.

Remove the mushroom stalks and discard.

Brush the mushrooms with melted butter.

Fry the minced onions in the remaining butter until tender.

In a bowl, mix the fried onion and butter with whole wheat breadcrumbs, sausage meat, minced sage, salt, and pepper.

Divide the mixture evenly among the mushroom caps, stuffing each mushroom.

Place the stuffed mushrooms in a shallow ovenproof dish.

Pour 4 tablespoons of water into the bottom of the dish.

Bake in a moderate oven (approximately 350°F or 175°C) for 15-20 minutes, or until the mushrooms are tender and the filling is cooked through.