Preheat oven to 450 degrees F.
Roast potatoes: Toss potatoes with garlic, 2 tablespoons oil, and salt and pepper, to taste.
Arrange wedges in 1 layer in an oiled shallow baking pan. Roast in upper third of oven 15 minutes, then turn over. Roast until golden and cooked through, about 5 minutes more.
To make the salad: Whisk together shallot, vinegar, mustard, salt, and pepper, to taste. Add remaining oil in a slow stream, whisking until emulsified. Toss together greens, potatoes, tomatoes, 3 tablespoons of Parmigiano-Reggiano, and enough vinaigrette to coat.
Sprinkle remaining Parmigiano-Reggiano over salad and serve.
Recipe courtesy of Gourmet Magazine