Wash, dry and slice the tomatoes in half. Peel and slice the garlic cloves. Trim and slice the spring onions into small chunks. Place two skillets on the hob and bring to high temperature. Add some olive oil to both pans. Place the fish fillets skin-side down in one pan and leave to fry but turning the heat to medium-high.
Add the tomatoes and spring onions into the other pan, stir and cook for a few minutes, turning the heat down to medium. Add and stir in the garlic, capers, oregano, balsamic glaze, salt and black pepper.
Turn the fish over to slightly cook from the other side, this should only take a minute or two.
In the meantime, stir the vegetables one more time before plating the vegetables. Now add the fish, skin-side up on top of the bed of vegetables.
Sprinkle with basil leaves and some extra virgin olive oil. Serve immediately.