Preheat the oven to 220°C/425°F/gas mark 7. Line a roasting pan with parchment paper.
In a food processor, combine the flour and a pinch of salt. With the motor running, drizzle in 3½ tablespoons of the olive oil and a scant 100 ml (½ cup) warm water and process until the dough comes together. Wrap the dough in plastic wrap (cling film) and refrigerate for 30 minutes.
Arrange the eggplant (aubergine) and tomato slices in the prepared pan and lightly salt them. Sprinkle with the garlic and drizzle with the remaining 2 to 3 tablespoons oil. Roast for about 20 minutes, until the eggplant is tender. Remove from the oven and let cool; keep the oven on.
In a small bowl, combine the breadcrumbs, almonds, thyme, and red pepper flakes.
On a sheet of parchment paper, roll out the dough into a very thin rectangle. Arrange the roasted vegetables over the dough, leaving a 1-inch (2.5 cm) border uncovered, then sprinkle evenly with the breadcrumb mixture. Fold the long edges toward the centre. Starting from one short end, roll up the dough to enclose the filling, using the parchment to help. Transfer the filled dough, still on the parchment, to a sheet pan.
Bake the strudel for about 30 minutes, until lightly browned. Serve warm or at room temperature.