Grilled Sirloin Steak W/mushroom

• 6 center top sirloin (cut)
• 120 ml dry wine (red)
• 80 gr mushrooms (fresh)
• 60 ml beef stock
• 28 gr butter
• 26 gr tomato paste
• 16 gr onion
• 8 gr flour
• 7 ml lemon pepper mushroom-wine sauce
• 1 gr salt