Tom Yum Goong: Thai Hot & Sour Prawn Soup (Dtom Yam Kung)

Ingredients

• 4 green prawns
• 1 teaspoon vegetable oil
• 600ml water
• ½ stalk lemongrass, chopped
• 2 thin slices peeled galangal, chopped
• 1 kaffir lime leaf, chopped
• 3 small Thai chillies, trimmed and chopped
• 3 teaspoons fish sauce, plus extra for serving
• 2 shiitake or oyster mushrooms, sliced
• 3 grape tomatoes, quartered
• 1 lime, juiced
• 2 teaspoons deep-fried garlic or shallot
• 1 sprig coriander, leaves sliced
• Roasted chilli powder, for serving (see video)