Preheat oven to 325 degrees F.
Line a 9x5-inch loaf pan with greased parchment paper so it has handles on the side, for easy removal of the bread. Set aside.
In a small bowl, mix together the baking soda and sour cream and set aside.
In a medium bowl combine the fruits and nuts with 1/4 cup of the flour, toss to coat and set aside.
In a large bowl, beat together the butter and sugar until light and fluffy. Beat in the egg, then the orange zest, vanilla, then the sour cream and baking soda mixture.
Add the flour and salt, and mix just until combined.
Add the fruit mixture and stir well to distribute the fruit and nuts evenly.
Pour the batter into the prepared loaf pan.
Place a pan of water in the oven, on the bottom rack. Place the loaf pan on the middle rack.
Bake for 1 1/2 to 2 hours, or until a wooden skewer inserted into the center comes out clean. If the cake browns too quickly, cover it loosely with foil.
When done, remove to a rack to cool for 10 minutes in the pan. Using the edges of the parchment paper lift the cake out of the pan and cool completely on the wire rack.
Wrap tightly with plastic wrap and then in aluminum foil to store.
Before wrapping, you can poke a few holes over the top of the cake and drizzle on a few ounces of brandy or bourbon, this will actually help if you intend on storing the fruit cake for a while.