Make the marinade by combining 1 tablespoon each of ginger and scallion, 1½ teaspoons of soy sauce, 1 teaspoon hoisin, and 1 clove garlic in a glass or ceramic container. Cut tofu into ½-inch pieces and add to marinade. Turn gently to coat. Let stand for at least 30 minutes.
When ready to cook, spray a wok with cooking oil spray and add 1 tablespoon oil. Set over medium-high heat and add ½ tablespoon ginger, 1 tablespoon scallion and 1 clove garlic. Cook 30 seconds.
Reduce heat to medium and add green beans, red peppers, and carrots and cook, stirring gently, 12 minutes, or until soft. Transfer vegetables to a platter and return wok to heat.
Add mushrooms and remaining ginger and garlic; cook, stirring frequently, 8 to 10 minutes, or until mushrooms release their liquid. Spray again with cooking oil spray if pan becomes too dry. Add mushrooms to vegetable platter.
Add bean sprouts to wok, spray again with cooking oil spray if necessary, and cook 4 to 6 minutes, or until sprouts wilt slightly.
Add tofu and marinade and cook, stirring gently, 2 minutes. Return vegetables to wok, add 1 tablespoon water, 2 teaspoons hoisin, and 1 tablepsoon soy sauce. Cook until heated through.