Pork Tenderloin in Pan Sauce without milk

2 slices bacon 1 -1 1/2 lb pork tenderloin 1/3 cup chopped onion 1 tablespoon butter or 1 tablespoon margarine 1 (8 ounce) can tomato sauce 3 tablespoons[...]

1/2 cup beef stock 1/8 teaspoon thyme 1/8 teaspoon rosemary 1 lb mushroom , caps sliced, stems reserved (mixed varieties) 2 -3 tablespoons canola oil 4 slices[...]

2 (1 1/2 lb) pork tenderloin, trimmed, about 1-1 . 5 lb each 4 slices pancetta or 4 slices bacon , chopped 1 medium shallot , minced 1 garlic clove , smashed[...]