Peel and finely chop the onion and garlic cloves. Heat up a non-stick pan, then add them to the pan and spray the olive oil (2 puffs should be enough). Stir for one minute to release the fragrance.
Add half of the cherry tomatoes, the tomato passata and half of the water. Put the lid on and leave to simmer for 15 minutes on low heat. Stir from time to time.
Take the lid off, and remove the cherry tomatoes skins from the pan - they should be easily removable with kitchen tongs. Gently mash the remaining pulp in the pan with a fork. Season with salt and pepper.
Add the olives, the remaining cherry tomatoes and water, cook for another 10 minutes with the lid on on medium heat.
In the meantime, heat a non-stick flat frying pan. Season the sea bream files with salt and pepper, then grill skin-on for 3-4 minutes, flip and grill for 2 more minutes.
Take the lid off the pan, taste and season with salt and pepper if needed.
Add the grilled sea bream to the pan.
Garnish with freshly cut parsley just before serving.
This goes well with whole-wheat bread as side dish, or you can try it with rice. Or just enjoy it as it is :)
Notes
Number of calories mentioned here do not take into account the side dish.