Individual Beef Wellingtons With Mushroom Sauce

• 8 beef rib eye steak
• 2 eggs (separated)
• 1 onion
• 325 gr bread crumbs (fresh)
• 180 gr pkg puff pastry
• 160 gr mushrooms
• 55 gr butter
• 20 ml water
• 3 gr salt
• 1 gr thyme