Method

• 1.
  Preheat oven to 200°C. Line a large baking tray with non-stick baking paper.
• 2.
  On a lightly floured surface, roll out pastry to a 30 x 15cm rectangle. Transfer to tray and brush with beaten egg. Use a fork to prick the surface. Place pastry in the fridge for 10 minutes to chill (chilling the pastry helps prevent shrinkage).
• 3.
  Cook pastry on the middle shelf of the oven for 20-25 minutes until slightly risen and golden brown. The pastry can be cooked in advance and kept at room temperature until ready to serve.
• 4.
  For onion marmalade, heat olive oil in a frying pan over low heat and add onions. Cook for 10 minutes or until soft. Increase heat to medium and cook until onions start to brown. Add verjuice or water and brown sugar. Cook until the liquid has been absorbed. Add balsamic vinegar and redcurrant jelly and cook until the mixture is a soft, jam-like consistency.
• 5.
  Just before you are ready to serve, slice tomatoes and mozzarella into 1/2cm slices.
• 6.
  Spread onion marmalade over the top of the pastry - it will crumble and crack a bit. Alternate tomatoes and mozzarella in two lines over the marmalade and drizzle with the oil. Return to oven and bake for no more than 5 minutes to heat through.
• 7.
  Garnish with basil and season with salt and freshly ground black pepper.