Remove tofu from package and drain by cutting in half horizontally. Place each half on paper towels and let stand, patting the tops and sides with paper towels. Combine 2 tablespoons soy sauce and 3 tablespoons sake. Dice tofu into 1 inch cubes and transfer to a medium rectangular glass baking dish. Arrange in a single layer and pour 2 tablespoons of the soy sauce and sake mixture over cubes. Turn once to coat and let stand while you prepare the other ingredients.

Stir cornstarch into remaining sauce until it dissolves. Remove mushroom stems and thinly slice caps. Peel and mince ginger, chop garlic, seed and mince chile, chop green onions, seed and slice bell pepper into 1 inch long matchsticks. Rinse and drain shrimp. Arrange all vegetables separately on a plate or cutting board and place near the stove.

Boil water for pasta. Add spaghetti and cook for 12 minutes.

While pasta is cooking, heat oil over medium high heat in a wok or large frying pan. Add mushrooms and cook 1 minute, until they just start to soften. Add ginger, garlic, chile, shrimp, and tofu with the marinade. Cook, stirring gently until tops of shrimp just begin to turn pink. Add green onion, bell pepper, and snow peas. Pour remaining soy sauce mixture over food and cook, stirring gently, until the red peppers are crisp tender, about 3 more minutes.

Drain pasta and place in a serving bowl. Top with stir fry and serve.