In a small bowl, whisk together vinegar, olive oil, mustard, salt and pepper. Set aside.
Heat a nonstick grill pan or skillet over medium-high heat. Coat with nonstick cooking spray; add tofu and grill 3 minutes per side. Remove to a plate and cut into bite-size pieces.
Toss salad greens with 3 tablespoons of the dressing and distribute evenly over 4 dinner plates. Arrange tofu, eggs, blue cheese and tomatoes on top. Serve remaining dressing on the side.
Serve with whole wheat rolls for a heartier meal.
