Blue Cheese Sauce, (recipe follows)
3 teaspoons walnut oil, or extra-virgin olive oil, divided
4 slices whole-wheat country bread
2 vine-ripened tomatoes, cut into 1/2-inch-thick slices
4 portobello mushroom caps, 3-4 inches in diameter
1 sweet onion, such as Vidalia, cut into 1/2-inch-thick slices
Salt & freshly ground pepper, to taste
2 cups trimmed arugula, or watercress
2 tablespoons chopped walnuts