Prepare the Pastry: In a large bowl, combine the flour and salt. Add the cold butter cubes. Using your fingertips, a pastry blender, or a food processor, cut the butter into the flour until it resembles coarse breadcrumbs with some pea-sized pieces of butter remaining. Gradually add the ice-cold water (and vinegar, if using), one tablespoon at a time, mixing until the dough just comes together. Be careful not to overmix. The dough should feel cool and slightly shaggy. Form into a disc, wrap tightly in cling film, and chill in the refrigerator for at least 30 minutes, or up to 2 days.

Prepare the Filling Base: While the pastry chills, prepare your creamy base. In a small bowl, combine the goat's cheese (or cream cheese), minced garlic, fresh thyme, and fresh oregano. Season with a pinch of salt and a good grind of black pepper. Mix thoroughly until everything is well combined and the mixture has a soft, spreadable texture. Set aside.

Slice and Drain Tomatoes: Wash and thinly slice all your tomatoes. For larger tomatoes, quarter or halve them before slicing to manage their size. Arrange the sliced tomatoes on a clean kitchen towel or paper towels and gently blot to remove excess moisture. This step is crucial to prevent a soggy bottom on your galette later. You want them to feel slightly drier to the touch.

Assemble the Galette: Preheat your oven to 200°C (180°C fan/Gas Mark 6). Lightly flour a clean work surface. Roll out the chilled pastry disc into a rough circle, about 30-35cm in diameter and 3-4mm thick. Don't worry about making it perfectly round; the rustic look is part of its charm. Carefully transfer the pastry to a baking tray lined with baking parchment.

Add Filling and Tomatoes: Spread the goat's cheese mixture evenly over the pastry, leaving a generous 4-5cm border around the edges. Arrange the sliced tomatoes on top of the cheese mixture, overlapping them slightly, in concentric circles or any pattern you fancy. Drizzle the tomatoes with the olive oil and season lightly with salt and pepper. Gently fold the pastry edges over the tomato filling, creating pleats as you go, leaving the centre of the galette exposed. The pastry will have a slightly rough, folded appearance.

Bake the Galette: Brush the folded pastry edges with the beaten egg wash. If desired, sprinkle the egg-washed pastry with sesame or nigella seeds for extra texture and flavour. Place the baking tray in the preheated oven and bake for 40-45 minutes, or until the pastry is a deep golden brown all around and the tomatoes appear slightly caramelised and softened, their scent filling your kitchen with a wonderfully aromatic fragrance.

Cool and Serve: Once baked, carefully remove the galette from the oven. Let it cool on the baking tray for at least 10-15 minutes before attempting to slice it. This allows the filling to set slightly and prevents it from crumbling. Garnish with fresh basil leaves before serving. The galette should feel firm to the touch when ready to serve, holding its shape beautifully.