Thai chicken broth - El Sitio Porcino

Ingredients

• 2 citronella (lemon grass) stalks
• 600 ml/1 pint chicken stock
• 2 onions, thinly sliced
• 1 garlic clove, finely chopped
• 2.5 cm/1 inch piece of fresh root ginger, peeled and grated
• 400 ml/14 fl oz coconut milk
• Juice of Vz lemon
• 2 tablespoons chopped fresh coriander
• 2 tablespoons nuoc-mam (fish sauce)
• Salt and freshly ground black pepper