Preheat the oven to 200 C/400 F. Line a large baking tray with parchment paper and set aside.: You should feel the warmth and hear the oven fan settle as the temperature climbs, and the aroma of heated enamel quietly builds. Preheating ensures the loaf meets a hot environment immediately, which helps form a crisp, golden crust. A well lined tray prevents sticking and makes transfer effortless. A common mistake is not waiting for the oven to fully reach temperature, which can lead to a denser loaf and pale crust. If your oven runs cool, consider using an oven thermometer to confirm accuracy.
In a small bowl, add the milk of choice with vinegar and let sit until it curdles, around 10 minutes.: The mixture will develop tiny curdled bits and a faint acidic scent, similar to buttermilk. This change is subtle, but visible as the surface may become slightly thicker and show small clumps. This acidity is what activates the baking soda and creates lift, so patience here pays off. Avoid rushing the step by using the liquid too soon, as it will not react fully and your loaf may lack its gentle rise.
In a large mixing bowl, add the flour, salt, sugar, and baking soda and mix well. Using a 1/2 cup, add your curdled milk into it in two increments, and mix gently, until just combined.: You will notice the dry mix loosening as the wet addition binds it. The dough should come together but remain slightly sticky; that tackiness indicates good hydration. Mixing gently preserves some air and prevents overworking the gluten, keeping the crumb tender. A frequent error is overmixing, which tightens the dough and results in a tougher loaf. Stop as soon as there are no dry streaks, even if the surface looks shaggy.
Lightly flour a kitchen surface. Sprinkle a tablespoon of flour on top of the dough and transfer to the floured surface. Gently knead the dough, around 8-10 times, and form a dome shape. The dough should still be quite sticky. Using a sharp knife, slice twice across the dough, forming a cross shape, around half an inch thick.: The kneading feels tactile and slightly sticky against your palms, but it will form a cohesive dome if handled gently. The light dusting of flour prevents excessive sticking without drying the dough. The cross score lets steam escape and gives the loaf its character when baked. If you press too hard while kneading, you may compress the air pockets and end up with a denser crumb, so be gentle and deliberate.
Transfer the bread dough onto the lined tray. Bake for 20-25 minutes, checking around the 20 minute mark. The bread is cooked when golden brown on the tops and when tapped, makes a hollow sound from the base.: As the loaf bakes you will smell a toasty sweetness and see the crust deepen to golden brown. The hollow tap is a classic auditory signal of doneness, indicating internal steam has escaped and structure has set. If the top browns too quickly, tent with foil to prevent burning while the interior finishes. A common pitfall is underbaking, which yields a gummy center; if unsure, leave it in for a few extra minutes and check again.
Remove from the oven and allow to cool on the tray completely, before slicing and toasting.: Cooling lets the crumb finish setting and prevents a gummy texture when sliced. The loaf will emit gentle residual steam and the crust will firm up as it cools. Resist the urge to slice hot bread, as it can compress the interior and become gummy. If you need to serve sooner, slice carefully and allow the internal steam to disperse for a few minutes before spreading with toppings.