Heat the 3 tablespoons of oil in a large saucepan, add the onions, cover and cook for approximately 10 minutes until tender but not browned. Add the garlic, tomatoes with their liquid, basil and wine.
Simmer gently uncovered, stirring occasionally, until liquid has disappeared and mixture is quite thick – about 20 minutes. Add the mushrooms and cook for a further 15 minutes or until all liquid has boiled away. Mixture must be quite dry. Season and allow to cool.
When cool assemble the strudel with defrosted filo. Use filo approximately 12in x 8in, which can go in the average oven tray/sheet. Set oven at mark 200°C/400°F/gas mark 6 if cooking straight away.
Brush tray with olive oil, put the first layer of filo on the tray and brush with oil, sprinkle a third of the nuts on; lay on top another sheet of filo brushed with oil and sprinkled with nuts. Repeat a third time. Add a fourth layer of filo, brush with oil and put on tomato/mushroom mixture and spread out. Roll the whole thing up like a swiss roll.
Bake for approximately 30 minutes until golden brown.
Serve with port wine sauce and your favourite Christmas veggies.