Preheat the oven to 450°F.
Place the whole chicken in a baking dish. Stuff the cavity with coarsely chopped white onion and 2 big sprigs of tarragon. Sprinkle some onions and tarragon around the chicken, too. Butter the chicken liberally on all exposed skin with the 4 tablespoons butter, then pour over it the dry white wine, water, soy sauce, plus Kitchen Bouquet for color. Grind black pepper on top.
Bake, covered loosely with foil, for 15 minutes, then turn down the heat to 350° and continue cooking until tender, approximately 45 minutes. Uncover and broil, adding a little butter on the top, for 5 to 7 minutes until well browned. Turn off the oven. To make gravy, pour off juices of the chicken into a saucepan. Boil and whisk in Wondra to thicken slightly, as desired. Slice chicken and serve with the sauce.
Chef's Notes:
Editor's Note: I substituted vegetarian Better Than Bouillon for the Kitchen Bouquet and 1 tablespoon pastry flour for the Wondra, boiling and whisking the sauce for 5 minutes to reduce to a thickness of heavy cream.