I finally found a sturdy recipe in Saveur magazine that produced a robust loaf, but found it lacking in sweetness, and containing far too few raisins.
This is my adapted recipe, sweeter, and with double the raisins. I also used both baking powder and baking soda (and more than the original recipe) to give it a bit more leavened character.
There are soda breads out there that add caraway seeds to the loaf. This is to be understood as an abomination.
4 cups flour
3/4 cup sugar
1 tsp salt
1 tsp baking powder
1/2 tsp baking soda
4 Tbp butter
2 cups raisins (I use a cup each of black and golden raisins)
1 egg, lightly beaten
2 cups buttermilk
(N.B. If you don't have buttermilk, use sweet milk that's been soured with a couple teaspoons of vinegar, or use sweet milk, omit the baking soda, and increase the baking powder to 2 tsp.)
1. Preheat oven to 425°. Grease a cast iron, 10-inch skillet with baking spray. Set aside.
2. In a mixing bowl, work butter into flour until it resembles coarse meal, just as you would do for baking soda biscuits or scones. Add sugar, salt, baking soda, baking powder, and raisins. Mix well.
3. Make a well in the center of the flour mixture. Beat egg in buttermilk, pour into the well, and mix with a wooden spoon until dough is too stiff to stir. Dust hands with a little flour, then gently knead dough in the bowl just long enough to form a rough ball. Transfer dough to a lightly floured surface and shape into a round loaf.
4. Transfer dough to the greased skillet. Using a serrated knife or kitchen scissors, score top of dough about 1/2'' deep in an "X" shape.
5. Bake at 425°F for 15 minutes, then lower the temperature to 400°F and bake 20-25 minutes more, until bread is golden and bottom sounds hollow when tapped with a knife.
6. Transfer bread to a rack to let cool.
Serve bread warm, at room temperature, or sliced and toasted.
Store tightly wrapped in plastic film or foil.
I imagine you could halve this recipe, but why would you want to?