Trim, peel, and chop <quantity>2</quantity> onions. Place them in a bowl

Trim and chop <quantity>1</quantity> leek. Add to the bowl

Crush <quantity>3</quantity> garlic cloves and add to bowl

Chop <quantity>1</quantity> carrot and add to the bowl

Drizzle extra virgin olive oil into a medium-large pot over high heat

Add the vegetables and stir. Cook until they are toasted

Add <quantity>2<unit>kg</unit></quantity> of fish carcass. Stir and slightly sear the carcass

Add <quantity>5<unit>L</unit></quantity> of water and bring to a boil. Reduce the heat to medium-low. and simmer for 45 minutes until it is reduced to 2/3

Strain through a fine sieve. The fish broth is ready

Use this broth as a base for risotto, fish sauce, or soup. Enjoy!