Mix the flours, salt, and baking soda in a medium-sized bowl. Making a well in the middle. Pour in 1 1/2 cups of sour milk/buttermilk. Stir with a spoon or using your hand until the dough just comes together. Add more sour milk/buttermilk if needed up to 1/2 cup.
Turn the dough out on to a lightly floured surface. Gently need a few times to form a smooth ball.
Press gently on the dough to form a flat 1 1/2 inch thick circle. Cut a 1-inch deep cross into the bread to "bless the bread" and prick each quarter with the knife to "let out the fairies". This lets the steam out of the bread allowing it to bake more quickly and gives it it's signature look.
Place the dough in a parchment paper-lined cast iron dutch oven, cover and bake for 15 minutes. Then lower the temperature to 400 ºF for 20 minutes or until the bread sounds hollow when you tump the bottom of the bread with your thumb. Uncover the bread for the last 10 minutes of baking.
If you do not have a dutch oven you can bake the bread in cast iron skillet or on a sheet pan. I prefer the dutch oven method because it more closely resembled how bread was cooked over coals in the 1800s but it is not necessary.
Allow the bread to cool if you can resist. This allows the bread to have a better texture. Slather with butter and serve alongside your favourite Irish meal. Or simply top it with a bit of butter and jam and enjoy it with a cup of tea.
Recipe by Nourishing Simplicity at https://nourishingsimplicity.org/2019/03/traditional-irish-soda-bread.html