Cook pasta according to packet directions. Drain, then return to pan.
Meanwhile, drain oil from tuna; reserving half. Place capsicum, tomatoes, spring onions, garlic and reserved oil onto a large baking tray lined with baking paper. Toss to coat. Bake for 15 minutes or until vegetables are soft.
Add tuna, roast tomato mixture (including juices) and basil to pasta. Toss to combine and serve.