In a bowl add: cherry tomatoes, olives, sundried tomatoes, onion, oil, salt and pepper. Mix.
On a large piece of baking paper add 2 slices of lemon and lay the fish on top. Repeat on another piece of baking paper.
Add the cherry tomatoes salsa on top, dividing equally on both fish.
Now wrap the baking paper around the fish like it was a parcel (fold one side then the other, and same for the top and bottom).
Bake for ~12mins at 180C fan oven. Fish is considered done when it reaches an internal temperature of 63°C (145°F) at its thickest part
Once out of the oven, carefully, drain the excess water in the sink (be careful, it will be piping hot!)