Classic Mock Meatloaf with Mushroom Gravy

Name: Classic Mock Meatloaf with Mushroom Gravy
Ingredients: 9 slices (8 ounces) commercial whole wheat bread (such as Arnold or Pepperidge Farm); 2 cups (8 ounces) walnuts; 3 large eggs; 3 medium onions, diced; 1 small green bell pepper, diced; 1 small celery rib, minced; 1 small bunch parsley, stems discarded and leaves chopped; 2/3 cup canned crushed tomatoes or 1 (16-ounce) can diced tomatoes, drained very well; 1 1/2 tablespoons canola oil; 1 teaspoon poultry seasoning; 1 teaspoon salt; Generous seasoning freshly ground black pepper; 4 tablespoons unsalted butter; 2 cups (8 ounces) thinly sliced mushrooms; 1/4 cup unbleached flour; 2 1/2 cups vegetables stock, store-bought or homemade; 1/4 cup dry red wine; 2 tablespoons tamari soy sauce; Freshly ground black pepper to taste