Heat oil in a non-stick skillet over medium-high heat. Stir in onion and mushrooms; cook 5 minutes or until softened and lightly browned at edges. Stir in spinach and red pepper flakes. Remove skillet from heat and set aside.
In a blender, add the 1/4 cup sun-dried tomatoes and puree until smooth; set aside.
Preheat oven to 350 degrees.
On a lightly floured work surface, cut dough into 6 equal pieces. With a rolling pin, roll each piece into a 6-inch diameter.
Spread 1 teaspoon of the sun-dried tomato paste over 1 dough circle. Place 1 slice of beef in center. Top with a half slice of provolone, some of the mozzarella, some of the vegetable mixture, a piece of the roasted red pepper, and some Parmesan cheese. Fold circle of dough in half and press with fork to seal edges.
Place calzone on a foil-lined baking sheet that has been sprayed with cooking spray. Repeat with remaining dough and ingredients.
Bake approx. 30 minutes or until evenly browned and heated through.