Spicey Wine Pot Roast

• 1 onion
• 525 gr top loin steak
• 240 ml water
• 60 ml tomato sauce
• 60 ml wine (red)
• 10 ml mustard
• 5 ml worcestershire sauce
• 1 gr mixed herbs (dried)
• 1 gr garlic powder
• 1 package brown gravy mix