Preheat the broiler.
For the pesto: Combine the sun-dried tomatoes, olive oil, Parmesan, pine nuts and basil in a food processor. Pulse until the mixture forms a coarse paste.
For the crostini: Spread the crostini with the mustard. Top with the turkey, then spoon over the gravy, followed by the pesto. Sprinkle with the Parmesan.
Broil until golden brown and bubbling, 2 minutes. Serve warm or at room temperature.