Sautee first 4 ingredients until translucent 2-4 minutes. Deglaze with the wine and stock. Add the clams/muscles cover and steam until just open. While cooking thoroughly mix the next 8 ingredients in a small bowl. When clams open pour the steaming liquid into a saucepan, adding the cornstarch mixture and heat until thickened. Sprinkle the clams with the tomatoes and parsley, then pour the thickened sauce over the top. Toss to coat and pour into a large serving bowl. Serve with toasted crostini's.