Salisbury Steak with Onion Gravy

INGREDIENTS

• 1/4 cup safflower oil
• 1 large onion, grated (about 1 1/3 cups)
• 2 slices white bread
• 1/2 cup whole milk
• 2 pounds ground sirloin
• 2 garlic cloves, minced (1 1/4 teaspoons)
• 1 large egg
• 2 tablespoons chopped flat-leaf parsley
• 2 teaspoons plus a dash of Worcestershire sauce
• Coarse salt and freshly ground black pepper
• 1 teaspoon cornstarch, plus 1/4 cup for dusting
• 1 1/2 cups beef broth