Prepare the Glass Noodles: Boil water in a medium pot, add glass noodles, and cook for 3-5 minutes until soft but firm. Drain and rinse with cold water.

Create the Broth: In a large pot, combine dashi, soy sauce, mirin, and sesame oil. Heat over medium until simmering, about 5 minutes.

Add the Vegetables: Add mushrooms, spinach, and any other desired vegetables to the broth, cooking for 3-5 minutes until tender.

Mix in the Noodles and Protein: Stir in the cooked glass noodles and chosen protein (tofu, chicken, or shrimp). Heat for an additional 2-3 minutes.

Final Touches and Serve: Remove from heat, ladle into bowls, and garnish with green onions and a drizzle of sesame oil.