Pre-heat the oven to 180C/200C fan ovens/gas mark 6
First prepare the tomatoes. With a small sharp knife, remove the green 'eye' as this can be tough and bitter to eat. Sit the tomatoes cut side up in a roasting tray then scatter over the chopped garlic, caster sugar and season with salt and pepper. Pour over a little olive oil and sit the lemon wedges next to the tomatoes, cut side down.
Roast in the oven for about 25 minutes until the tomatoes are rich and juicy, and the lemon wedges are golden and caramelised. By roasting the lemon wedges you get a sweeter flavoured juice to squeeze over the cooked salmon.
To make the gremolata, place the capers, parsley, lemon zest, olives, about 2 tbsp olive oil and a good twist of pepper in a pestle and mortar, then pound to a rough paste. Alternatively blitz briefly in a small food processor, or finely chop the parsley, capers, lemon zest and olives together, then mix with the oil and seasoning.
Spread the gremolata over the top of the salmon fillets and sit on a baking tray brushed with a little oil to stop the salmon sticking. Place in the oven with the tomatoes for about 8-10 minutes until just cooked through.
Serve the salmon with the roasted tomatoes and a roasted lemon wedge each to squeeze over the salmon. Serve as it I or with some cooked new potatoes or a green salad.