Preheat the oven to 190°C I have a fan oven so adjust to suit your own appliance.
Cut a piece of tin foil big enough to put your piece of fish on. Using a spray oil (FryLight) spray a piece of tin foil before placing the fish in the centre of the foil and wrapping the fish up like a parcel. This will stop the fish sticking to the foil.
Next cut the cherry tomatoes into small pieces and sprinkle over the fish then do the same with the spring onion. Add the lemon juice and a drop of olive oil, season with salt and pepper and wrap the parcel up tightly.
You will now have a foil parcel of fish ready for the oven.
Cook in the middle of the oven for around 20 mins, checking after 15 by carefully unwrapping the top of the parcel and checking the colour and texture of the fish.
To serve open up the parcels and place the fish on a plate using a fish slice before pouring over the tomato and onions and the juices.