Recipe modified from Joy of Cooking (older version published in 1964). Makes a dozen muffins.

1¾ cups all purpose flour*
2 tablespoon cornstarch*
1 teaspoon baking soda
½ teaspoon salt
¼ cup sugar
¼ cup coconut oil
½ cup dried currants (or raisins/cranberries slightly chopped or mini chocolate chips!)
1 cup buttermilk¹If you don’t have buttermilk on hand you can use 1 tablespoon of white vinegar and then fill the cup the rest of the way up with milk. Remember you need that acid for the baking soda + that milk curdle!
Coarse sugar for topping

1. Preheat the oven to 400° F (200° C). Prepare a muffin pan with liners (disposable or I use something like these silicone ones) or grease.
2. In large bowl combine flour, cornstarch, baking soda, salt and sugar. Stir together. (If you really want to be thorough then sift them)
3. Add in coconut oil and combine it into the flour. I use my fingers for this because, why not! It melts the coconut oil a bit and you can really feel when it has reached a smaller grain. It should resemble coarse meal when it is ready, you shouldn’t feel any big oil chunks.
4. Add in buttermilk and stir – slightly. Only until just all incorporated together. Do not over stir. ²This has to do with using baking soda. Rising starts immediately when the acid hits the sodium bicarbonate. Get it in the oven as fast as possible for the best rise!!!
5. Add in currants and fold a few times to evenly distribute.
6. Spoon out batter, it will be very sticky – I use two spoons to do it, evenly into the 12 muffin tins.
7. Top with coarse sugar if desired.
8. Place in middle rack of oven and cook for 20 to 25 minutes. Test doneness by sticking a toothpick into the muffin. If it comes out clean it is done.
9. Remove and allow to cool in the tin for a few minutes then transfer to wire rack. If you are using silicone liners I suggest removing the muffins from the liners at this point or they will condensate in the liners.

Notes:

* The combination of all purpose flour and cornstarch is like using cake flour. If you have cake flour you can instead use that. I don’t bother with it and find that cornstarch works fine whenever I need it (and I always have a ton of cornstarch around because I used it in all my fried recipes too). I think my next science discussion needs to be what cornstarch does when mixed with flour 🤔.

Rambles:

Saint Patrick’s Day is just around the corner so let’s talk about leavening agents. No relation you say? I disagree. This is the perfect time to understand a key leavening agent you use all the time because it is involved in one of those recipes that is apparently an “obligatory Saint Patrick’s Day food” – Baking Soda in Irish Soda Bread!

I first delved into the science behind baking powder and baking soda back in my Chocolate Sourdough Baked Donuts recipe when I noticed a distinct difference in the rising of the donuts. I have a masters degree in biochemistry and cell biology but I was guilty of never really thinking about the science of the ingredients I was working with. This was silly of me, it can make a huge difference in your recipes. Especially recipes like Irish Soda Bread.

So what is happening here? There is a great article over on The Kitchn about it but I will summarize it here. Sodium bicarbonate (baking soda) when heated or when combined with an acid will result in the formation of carbon dioxide bubbles. This results in the rising of the bread. The advantage of the acid is that it helps this process go quicker and it reduces the alkaline taste usually associated with sodium biocarbonate. This is why you want/need buttermilk in this recipe. Buttermilk has the acid that is needed to produce the reaction with the sodium bicarbonate. If you substitute regular milk with buttermilk, traditional Irish Soda Bread won’t rise.

I say traditional because this is only the case if you use JUST sodium bicarbonate (baking soda). What happens if you use some baking powder? Baking powder is baking soda but with acid already mixed in at the “perfect” amount. If you look at the ingredients in your baking powder container you will see monocalcium phosphate (the acid in essence but a little more complicated then that), sodium bicarbonate (baking soda – alkaline), and cornstarch. This creates a mixture that does not need an additional acid source in order to rise but also doesn’t leave that alkaline taste in your baked goods. This is great for your cake when you aren’t adding anything acidic to it and where the little bit of cornstarch only makes it more fluffy. But why isn’t it perfect when you have some acid in your recipe? This is because it already has acid in it at the desired ratio and if you add it to more acid it will probably taste a little too acidic. Here it all is in VERY simplified equation form:

Baking Soda + Heat = Carbon Dioxide + Alkaline Taste
Baking Soda + Acid + Heat = Carbon Dioxide

Baking Soda + Acid (monocalcium phosphate) + Cornstarch = Baking Powder

Baking Powder + Acid + Heat = Carbon Dioxide + Acidic Taste
Baking Powder + Baking Soda + Acid + Heat = Carbon Dioxide

Thus many find the combination of baking powder (for the rise and flavor) and baking soda (to interact with the acid for more rise and reduce acidity) is perfect for those type of baked goods.

Now what does this have to do with this recipe? I don’t like to eat that much Irish Soda Bread. I usually enjoy one slice at a time and then what do I do with the leftovers? I hate wasting food and I find that Irish Soda Bread dries out pretty quick. That is when I thought, what about muffins? Muffins are the perfect size amount of Irish Soda Bread I want, plus perfect for serving to many people or giving to friends!

Because I decided to make muffins, I wanted a recipe that was super light and fluffy and not as dense as regular soda bread. Paying attention to science and ingredient knowledge this time, I tried many different combinations of baking soda and baking powder until I found what I liked best. To my pleasant surprise it was actually the recipe with straight baking soda and no baking powder. Thus the recipe below. This recipe can have a VERY slight (I had to really search for it…maybe even at the “it was the power of suggestion” slight) of that alkaline taste to it. I however found that reminiscent of soda bread I have had in the past and enjoy it, especially because the muffins are so small. If this flavor really turns you off, use 2 teaspoons of baking powder + ½ teaspoon baking soda instead of what is listed below.