Cut tomatoes in half, roast for 30 minutes cut side up on a lightly greased oven tray. Remove skins and process the tomatoes.
Dry roast pine nuts under a griller until lightly browned.
Remove spinach leaves and wash thoroughly. Cook lightly in a saucepan for 2-3 minutes. When cooled, squeeze out the extra fluid and chop.
Brush the tuna with olive oil and set aside. Bring a saucepan ¾ full of salted water to the boil. Add the pasta and cook until al dente.
In a saucepan, fry the onion, garlic and herbs in the olive oil until onion is transparent. Add chopped tomatoes and tomato paste. Add spinach, pine nuts, salt and pepper. Cook on low for about 5 minutes. Sear the tuna for approx 2 minutes each side then serve on a plate with the pasta spirals and tomato and spinach sauce.