Rib Roast With Garlic Crust

• 10 onions
• 2 heads garlic (whole)
• 1 beef bouillon cube
• 3,600 gr three rib beef roast
• 375 gr carrots
• 250 gr parsnips
• 60 ml dry wine (red)
• 5 gr parsley (chopped)
• 3 gr cracked black pepper
• 3 gr tarragon (minced fresh)