Antipasti Stuffed Chicken

Name: Antipasti Stuffed Chicken
Ingredients: Vegetable oil cooking spray; 1/2 cup red wine vinegar; 2 teaspoons dried oregano; 1 teaspoon ground fennel seed; 1 teaspoon Dijon mustard; 1 teaspoon kosher salt; 1 teaspoon freshly ground black pepper; 1 large clove garlic, minced; 1 cup extra-virgin olive oil; 6 slices Genoa salami (2 ounces), chopped; 4 thin slices prosciutto, chopped; 4 slices provolone cheese (4 ounces), chopped; 4 large pepperoncini, stemmed, chopped; 4 oil-packed sundried tomato halves, chopped; Four 6-ounce boneless, skinless chicken breasts; 4 cups baby arugula (about 4 ounces), lightly packed