1 lb ball whole-wheat pizza dough, room temperature (TIP: Make your own dough with [url href="http://www.cleaneatingmag.com/recipes/vegetarian/ce-whole-wheat-pizza-dough/"]CE's recipe[/url])
1/2 cup balsamic vinegar
Olive oil cooking spray
4 oz top sirloin steak
1/8 tsp each sea salt and ground black pepper
1 yellow onion, cut into thin 10-inch-long slices
2 cups arugula
1 tbsp plus 1 tsp crumbled blue cheese
Preheat oven to 450°F. Separate dough into 8 equal balls and flatten each into 1/4-inch-thick rounds. Arrange on parchment-lined baking sheets and bake until edges and bottoms are golden, about 10 minutes.
Meanwhile, in a small saucepan, heat vinegar on medium-high. Bring to a boil, reduce heat to medium-low and cook, stirring occasionally, until reduced by half, about 10 minutes.
Meanwhile, mist a grill pan with cooking spray and heat on medium. Season steak with salt and pepper. Add to pan and cook, turning once, until steak reaches desired doneness, about 10 minutes. Transfer to a cutting board and tent with foil.
To grill pan, add onion and sauté, stirring often, until golden brown. Remove from heat.
Thinly slice steak against the grain. Top crusts with onion, arugula, steak and cheese. Drizzle with vinegar and bake for 2 minutes, until cheese is bubbly.