"Create a soba noodle bowl recipe using cooked soba noodles rinsed in cold water, vegetable broth, soy sauce or teriyaki sauce (choose the better option and explain in the recipe notes), sesame oil, fresh ginger, mushrooms, boiled egg, and spinach. Include suggested additional toppings or mix-ins that pair well. Make it clear, flavorful, and easy to follow. Use imperial units."