Tomato-y Beef and Mushroom Gravy

2 cups beef broth or prepared beef base1 1/2 teaspoons olive oil4 ounces shiitake mushrooms, tough stems removed and caps thinly sliced2 tablespoons all-purpose flour2 tablespoons ketchupSalt and pepper to tastePlace a small saucepan over medium heat and add the broth. Bring to a lower simmer and reduce heat.To a medium saucepan add olive oil and place over medium heat. When oil is hot, add mushrooms and sauté briefly until softened. Add flour and ketchup and sauté until mushrooms begin to brown slightly.Add some of the mushroom mixture to the beef broth and stir until combined, then pour broth into pan with mushrooms and stir until no flour lumps remain. Bring to a low simmer and cook, stirring frequently, until slightly thickened. Remove from heat, taste and adjust seasoning with salt and pepper, and serve.Makes about 2 1/4 cups.Cook's note: To prepare broth from a base, add 2 teaspoons base to 2 cups water and stir until dissolved.Nutrition values per 2 tablespoons (without added salt): 11 calories (34.5 percent from fat), 0.4 g fat (0.05 g saturated fat), 1.5 g carbohydrate, 0.1 g fiber, 0.2 g protein, 0.4 mg cholesterol, 95 mg sodium.LeanNote: Since beef broth is so low in calories (11 per cup), it's impossible to use any oil in the preparation of gravy and end up with fewer than 30 percent calories from fat.