Step 1

Place oil, chilli flakes, chillies and garlic into mixing bowl and chop 5 sec/speed 7.

Step 2

Scrape down sides of mixing bowl with spatula and heat 4 min/Varoma/speed 2.

Step 3

Add galangal, eschalot, tamarind paste and shrimp paste (optional) and chop 10 sec/speed 10. Scrape down sides of mixing bowl with spatula.

Step 4

Add fish sauce, lemongrass, water, stock paste, Kaffir lime leaves, lime juice and reserved prawn heads and shells and heat 18 min/100°C//speed 2.

Step 5

Using a fine-mesh sieve, strain liquid into a jug and discard solids.

Step 6

Place prawn meat, mushrooms and strained liquid into mixing bowl and cook 5-8 min/90°C//speed 1, or until prawns are just cooked.

Step 7

Add tomatoes and cook 2 min/90°C//speed 1. Divide between serving bowls and garnish with coriander just before serving.