In a medium bowl, mix the pepper and onion mixture with the cheese and cornstarch. Season with salt and pepper to taste. Form the mixture into 8 balls, squeezing out any excess liquid. (The balls will seem loose.) Transfer the balls to a plate and freeze for at least 15 minutes.
Preheat the oven to 450 degrees F. Place a wire rack on a foil-lined baking sheet, and set it aside.
Put the flour in a shallow dish. Put the panko in another shallow dish. In a medium bowl, whip the egg whites with a whisk until they are extremely foamy but not quite holding peaks.
Working in batches, dredge the cheese balls in the flour, shaking off any excess. Add the cheese balls to the egg whites and toss to coat them completely. Add the cheese balls, a few pieces at a time, to the bowl of panko and coat completely.
Spread the balls on the wire rack. Spray them lightly with cooking spray. Bake the cheese balls until the breading is golden and crispy, about 5 to 7 minutes.
Meanwhile, combine the applesauce, jalapeños, and mustard in a small bowl. Season with salt and pepper to taste.
Serve the cheese balls immediately with the sauce.
Recipe courtesy of Now Eat This! Diet: Lose Up to 10 Pounds in Just 2 Weeks Eating 6 Meals a Day! by Rocco DiSpirito/Grand Central Life & Style, 2011.