In a mixing bowl, whisk together vinegar, soy, tahini, sesame oil, and sugar. Drizzle in canola oil to emulsify. Season. Toss with scallions, tofu, mushrooms, and cucumbers. Check for flavor. Plate salad and garnish with wedges of soy sauce eggs.
Soy sauce eggs:
Soft boil the eggs to the just-coagulated stage, and placed immediately in cold water.
Tap eggs gently all over to cover with cracks.
Add the eggs to pot filled with 1 cup soy sauce and 1 cup water (enough to cover 6 eggs), 1 slice of ginger, and half teaspoon of five-spice powder. Simmer over low heat for 25 to 30 minutes, then let steep for another 1/2 hour.
Crack open the eggs and peel them, then slice into wedges.