In a medium soup pot, heat coconut oil over medium low heat. Add garlic and ginger and cook and stir until aromatic, 1-2 minutes. Add sliced mushrooms, toss to mix, then add tamari and cook and stir 5 minutes more. Add vegetable broth and raise heat to simmer. Simmer about 10 minutes or until mushrooms are tender. Meanwhile, cook rice noodles in boiling water according to package directions, and drain. Stir noodles into soup and taste for seasoning. Add extra tamari if desired. Serve in bowls topped with the green onions and slivers of seaweed snacks.