Demi Glace

Bahan-bahan (3 porsi)

• 1 Tbsp extra virgin olive oil
• ½ onion ((3 oz, 85 g))
• 1 rib celery ((3.5 oz, 100 g))
• 1 carrot ((3 oz, 85 g))
• ½ tsp Diamond Crystal kosher salt
• freshly ground black pepper
• 1 Tbsp tomato paste
• 4 Tbsp red wine
• 8 cups beef stock/broth
• 1 bay leaf
• 1 tsp dried thyme
• 3 sprigs parsley
• 8 peppercorns
• 2 Tbsp unsalted butter
• 4 Tbsp all-purpose flour (plain flour)