Salisbury Steak Meatballs

Bahan-bahan (4 porsi)

• 2 tablespoons butter
• 1 cup diced onion (about 1 medium onion)
• 2 cups sliced mushrooms (about 8 oz mushrooms)
• 1 ½ pounds lean ground beef
• ⅓ cup Italian bread crumbs (or seasoned bread crumbs)
• ⅓ cup milk
• ¼ cup chopped fresh parsley (or 2 tablespooons dried parsley, plus additional for garnish)
• ¼ cup shredded Parmesan cheese
• ¾ teaspoon salt ( and ¼ teaspoon black pepper)
• 1 tablespoon all-purpose flour
• 2 tablespoons ketchup
• 1 ½ teaspoons Dijon mustard
• ½ teaspoon garlic powder
• 2 teaspoons Worcestershire sauce
• 1 ¼ cups beef broth
• ⅔ cup water