Medium-Rare Sous Vide Filet Mignon - A Duck's Oven

Ingredients

• 2 8 oz filet mignon steaks
• kosher salt
• freshly cracked black pepper
• 2 tbsp ghee
• 3 tbsp salted butter
• 1/4 cup all purpose flour
• 1 1/2 cups chicken stock
• 1/2 tsp kosher salt
• 1/4 tsp freshly ground black pepper
• 2 tbsp sour cream
• 1/4 cup crumbled blue cheese