Hamburgers with Cabernet and Sauteed Onions

Bahan-bahan (8 porsi)

• 4 medium onions, (chopped)
• ¼ cup (½ stick) butter
• 1½ pounds lean ground beef
• 1½ pounds lean ground sirloin
• 1 cup cabernet sauvignon
• 2 teaspoons celery salt
• 2 teaspoons dry mustard
• 1 teaspoon freshly ground black pepper
• ½ teaspoon salt
• ½ teaspoon garlic powder
• ½ teaspoon dried thyme
• 8 hamburger buns