Fill a small stockpot with 3 cups of water or vegetable stock and bring it to a boil. Season with salt, pepper, mushrooms seasoning, and toasted sesame oil.
Add the vegetables and seaweed. Cook until the vegetables are as crisp-tender as you like. Keep this soup over low heat while you cook the wonton.
Meanwhile, bring a large pot of water to a rolling boil. Use a large surface pot so the wontons have enough space to move around during cooking.
Slowly drop the wontons in and let them cook until they float up. Let the wontons stay afloat for a few more seconds.
Now, divide the soup into 2 bowls. Dish out the wontons and place them into the bowls.
Garnish with chopped onion, a drizzle of toasted sesame oil/shallot oil, fried shallots, and serve warm with a side of chopped Thai chile in soy sauce.