Pre-heat the oven to 190°C and line a baking tray with parchment.
In a large bowl, mix together the flour, salt, bicarbonate of soda and baking powder. Once combined, pour in the yoghurt, kefir or buttermilk and mix everything together. It is really important not to over-work a soda bread, so mix gently until a dough begins to form. As soon as the dough has formed, shape into a round and transfer to your lined baking tray.
Using a knife, score the top of the dough with a cross and place into the oven to bake for 35-40 minutes. The bread will be cooked when a golden crust has formed and when the loaf sounds hollow when tapped on the bottom.
Transfer the bread to a wire rack to cool while you make your homemade butter.
To make homemade butter, pour the cream into a food processor. Turn to a high speed and wait for the cream to whip. Continue beating until the cream splits – keep beating until a ball of butter forms in the bowl.
Transfer the butter to a sieve and strain off any residual buttermilk (preserving the buttermilk for your next loaf of soda bread). Once well strained, return the butter to a bowl and mix through your salt and any additional herbs or flavours you might like.