Heat the oil in a pan and gently fry the onion, garlic and ginger for 3-4 minutes, or until softened. Add the fish head and tail and lemongrass, stirring to coat in the oil, then pour over the boiling water and simmer for 6-8 minutes.
Strain the mixture through a sieve into a clean pan, then add the ketchup, Tabasco sauce and coconut milk and simmer for a further 2-3 minutes. Add the broccoli, grated coconut, chilli and lime juice and cook for 3-4 minutes, or until the broccoli is tender.
Ladle into bowls and serve immediately.
