Add salt to the water and heat over a low flame
When the water starts to steam (not boil) add the tuna and continue to boil over a low flame
As the broth cooks, some spume will rise to the surface – scoop these out at regular intervals
Keep on simmering on a low flame until there is no more spume
Add onion and curry leaves, if desired
Continue to simmer for at least 10 more minutes
Serve with rice or roshi
Serving Size 2 - 4 people