Pre-heat the oven to about 180 Celcius (around 350 Fahrenheit / Gas Mark 4), or perhaps just a little less. Lightly oil or grease a small (1Lb) loaf tin or lightly flour (or oil) a flat baking tray if you don't have / want to use a loaf tin. If substituting for the buttermilk with milk and lemon juice then do that now and put it aside. Sieve/sift the flour into a medium sized mixing bowl and add the salt. Scoop up handfuls and allow to drop back into the bowl to aerate the mixture. Add the Sultanas and if using them, caraway seeds and vitamin C powder. Stir together with a wooden spoon. Add and stir in the baking soda. Add enough of the buttermilk to make a soft dough. Now work quickly as the buttermilk and soda are already reacting. Knead the dough lightly - too much handling will toughen it, while too little means it won't rise properly. It should require a couple of minutes at most. Basically you're adding the buttermilk as you're kneading it just enough to work the ingredients together properly at which point it needs to be baked straight away in the hot oven. If using a baking tray rather than a loaf tin, then form a round loaf about as thick as your fist. Otherwise shape it to a similar size but such as will fit in the loaf tin. Place it on a lightly-floured baking tray and lightly cut a cross in the top with a floured knife "to let the faeries out so they don't jinx your bread", or just put it in the loaf tin and lengthways cut a line along the top. Put at once to bake near the top of the pre-heated oven. Bake for about 35-45 minutes. "When baked, the loaf will sound hollow when rapped on the bottom with your knuckles.". Wrap immediately in a clean tea-towel if you prefer the crust to be softer. This bread will keep well for a couple of days if very well wrapped. If unwrapped it will dry out very quickly - within half a day. It freezes beautifully. Best served slightly warm on its own or with butter. Note: The Rankin recipe that I was copying does not use caraway seeds at all and uses sultanas not raisins. Some Irish fruit soda bread recipes use caraway seeds and a larger number don't. I love caraway seeds but I like this bread best without. I've listed as a suggestion only. I use Bread flour because I have plenty and I imagine it gives a better rise but I understand that plain flour (All Purpose Flour) works just fine-never used it myself. Historical notes: There are hundreds or thousands of recipes, most of them contain egg or rice flour or cornflour etc. Such ingredients would not have been available to most poor Irish families in towns and cities. The point of Irish Soda Breads (as well as Scottish Shortbreads for that matter) was that it was made by a people so poor that they could not even afford to buy yeast (which was not readily available) to bake their daily bread and was basically the normal bread such as they baked every day which had sugar and fruit added as a special sweet and fruity Sunday treat because they couldn't afford to make a proper cake. It's convenient from a cutting point of view if you've got a very small loaf tin, but a flat or round baking tray will do fine. It was originally made as round loaf sitting on a griddle (UK: basically a form of frying pan) baked in a Bastible (an iron baking pot - a type of oven - they were made in Barnstable, Devon hence the name) over the glowing embers of a peat turf fire. Because of the way the bread rises it's not essential to be so accurate as it is with a yeast-based bread so volume measures (cups and spoons) could just as easily be used instead if you don't have a set of kitchen scales as would have been the case across Ireland in the early 1800s when they were first made.