Heat 80 ml of extra virgin olive oil in a large paella pan over medium heat. Add the finely chopped onion and cook for 8–10 minutes, until translucent.
Add the finely chopped garlic and cook for another minute, until fragrant, taking care not to let it burn.
Add the squid, increase the heat to medium-high and cook for 5–7 minutes, until it changes colour and releases its liquid.
Stir in the grated tomato and cook for 5 minutes, until the mixture has reduced and thickened.
Dissolve the squid ink in a little hot fish stock and stir it into the mixture until it turns a deep, even black.
Pour in the bomba rice and stir for 2 minutes, so each grain is well coated with the sauce and ink.
Add the hot fish stock and salt to taste. Scatter the prawns evenly over the rice. Bring to the boil over high heat for 5 minutes, then reduce the heat to medium-low and simmer for 13–15 minutes without stirring.
Remove from the heat, cover with a clean tea towel or aluminium foil, and leave to rest for 5 minutes. Serve with aioli to taste.