Patlıcanlı rulo börek (Turkish aubergine and pepper filo rolls)

Method

1. Spread the aubergine cubes over a large baking tray, sprinkle with salt and leave for 10 minutes to draw out excess moisture. Use a piece of kitchen paper to gently squeeze the pieces and remove even more liquid.
2. Heat 3 tbsp of the olive oil in a large frying pan over a medium-high heat, add the aubergines and cook for 10-12 minutes, stirring occasionally, until softened and starting to char around the edges. Transfer to a large mixing bowl to cool.
3. Heat another 2 tbsp of the olive oil in the same pan. Cook the onion and peppers for 10 minutes, stirring often, until softened and starting to brown a little. Tip into the bowl with the aubergines, add the tomato purée, season with salt and pepper and stir gently. Leave to cool for 10-15 minutes. Heat the oven to 180°C fan/gas 6 and line a baking sheet with baking paper.
4. Combine the egg white, milk, sparkling water and 1 tbsp olive oil in a bowl. In another bowl, beat the egg yolk with the remaining 1 tbsp olive oil.
5. Open the pack of filo and cover with a damp tea towel so they don’t dry out. Take a filo sheet and quickly brush with the milk glaze. Top with another sheet and brush again. Put about 200g of the filling in a line along one of the long edges. Roll gently into a log, sealing the edges with the milk glaze. Transfer to the prepared baking sheet and brush with the milk glaze. Make 2 more logs, spacing them 2cm apart. Halve the last sheet widthways, layer it up and use the remaining 100g filling. Slice each log into 8cm rolls, brush with the egg yolk mixture, then sprinkle with the sesame and nigella seeds.
6. Bake for 20 minutes or until golden and crunchy. Serve warm or at room temperature.