Preheat the oven to 180°C/gas mark 4. Lightly brush a 23cm-round springform tin with 1 tbsp oil, then layer up the filo pastry at different angles to line the tin, brushing with a little oil between layers. Chill until needed.
Heat the remaining oil in a large frying pan and gently fry the courgettes and broccoli for 3-4 minutes, then add the spring onions and cook for a further minute. Add the petits pois, then remove from the heat. In a measuring jug, mix together the eggs and milk, then season.
Put the vegetables in the tart case, then pour over the egg mixture. Top with the stilton and bake for 45 minutes until set and golden. Trim the pastry overhanging edges and serve with the salad and tomatoes.