Coat a 9x5 loaf pan with baking spray replacement, baking spray, or grease & flour it. Set it aside for now.
Peel and dice the peaches, discarding the pits and skins. Set them aside for a moment.
In a small mixing bowl, combine all-purpose flour, kosher salt, and baking soda. Give those a stir and set it aside for now.
In your mixing bowl, beat the butter until it is fluffy.
Add in the sugar and beat again until creamy.
Add the eggs, one at a time. Mix each in fully before adding the next.
Mix in the vanilla extract.
Add half of the flour mixture and stir it in.
Mix in the sour cream.
Add the other half of the flour mixture and mix well. Be sure to scrape the sides of the mixing bowl with a rubber spatula.
Fold in the diced peaches.
Spread the thick batter in your prepared loaf pan.
Sprinkle the turbinado sugar over the top of the cake (optional.)
Bake for 55-60 minutes, or until the cake tests done with a tooth pick.
Allow the cake to cool on a rack in the pan for 10 minutes. Then, carefully remove the cake to the rack and allow it to cool. This cake is very delicate, so do this gently.