Heat a sauté pan over medium-high heat and cook your chicken, veal, or pork until browned. Remove the meat and set aside, leaving the browned bits in the pan.
Add butter if needed, then sauté the mushrooms until they release moisture and begin to brown. Do not overcrowd the pan, or the mushrooms will steam instead of caramelize.
Add the shallots and cook for about 1 minute until softened and fragrant. Stir frequently so they do not burn.
Deglaze the pan with white wine. Scrape up the browned bits with a wooden spoon because those bits contain concentrated flavor.
Simmer the wine until reduced by about half. This concentrates flavor and removes harsh alcohol notes.
Add tomatoes and stock. Simmer gently until the sauce lightly coats the back of a spoon.
Taste the sauce before seasoning. Depending on the stock, you may need very little salt.
Whisk in cold butter off the heat for a glossy finish.
Return the meat to the pan briefly to warm through and coat with sauce before serving.
Notes
Serve with your wildest game meats, wild fowl or a domesticated New York Strip steak. It works well with all of them.