ramen broth recipe

#### Ingredients: - **4 cups chicken broth** - **4 cups pork broth** (can use additional chicken broth if preferred) - **1 tablespoon vegetable oil** - **1 onion** (quartered) - **2 cloves garlic** (smashed) - **1-inch piece ginger** (sliced) - **2 tablespoons soy sauce** - **2 tablespoons miso paste** - **1 tablespoon sake** (optional) - **1 tablespoon mirin** - **1 sheet kombu** (dried kelp, optional) - **1 cup dried shiitake mushrooms** (optional) - **Salt** (to taste)