Place ground sirloin in a large mixing bowl.

Create a well in the center of the meat.

Add the beaten egg to the well.

Add the Italian seasoned breadcrumbs to the well.

Add the finely chopped onion to the well.

Add the crushed and minced garlic cloves to the well.

Add the crushed red pepper flakes to the well.

Add the Worcestershire sauce to the well.

Add the chopped flat leaf parsley to the well.

Add the grated parmigiano or romano cheese to the well.

Season with coarse salt and black pepper.

Mix all ingredients until well combined, being careful not to over-mix.

Divide the mixture into 4 equal parts.

Roll each part into 4 meatballs.

Space the meatballs equally onto a nonstick baking sheet.

Place the baking sheet in the oven.

Roast for about 12 minutes.

Break a meatball open to check for doneness.

Ensure the meat is cooked through before removing from the oven.