Preheat the oven to 200°C / 400°F and line a baking tray with parchment paper.
In a bowl, combine the flour, olive oil, water, salt and herbs until a dough forms. Knead briefly, then let it rest for 5 minutes while you prepare the filling.
In a bowl, combine the fire-roasted tomatoes, beans and tomato paste (if using). Blend until smooth, or mash with a potato masher for a chunkier sauce. Season with salt and pepper.
Roll the dough into a large circle directly on the prepared baking tray.
Spread the tomato sauce over the dough, leaving a 4–5cm (about 2-inch) border. Top with the spinach, mozzarella and olives.
Fold the edges over the filling to create a rustic galette.
Bake for 30–35 minutes, until the pastry is golden and crisp and the cheese is bubbling.
Serve warm with a simple carrot salad, if desired.
