Ah, these were very soft!
For 8 (I made two batches to avoid letting the butter warm up while I was working with it)
2 cups all-purpose flour
1/3 cup + 1 tablespoon sugar
1 teaspoon baking powder
1/4 teaspoon baking soda
1/2 teaspoon salt
1/2 cup unsalted butter, frozen
1/2 cup sour cream, cold
1 egg
Zest from one lemon
6 oz fresh blackberries
Prep the butter by cutting into little cubes and placing in the freezer
Combine the flour, 1/3 cup sugar, baking powder, baking soda, and salt, and put it in the freezer while doing any other prep
Combine sour cream, egg, and lemon zest and place in freezer while working with the butter and flour
Oven 400 degrees
Work the butter into the flour with my fingers until I get a coarse meal (this takes time - I could use a food processor if I had one)
Add the (by this time) very cold wet ingredients and stir very gently with a fork until moistened and sort of holding together. Turn out onto a floured work surface. Smoosh it with the bottom of your palms just a couple of times to push the butter into layers, then shape into a 7-inch disk. Cut into 8 wedges and sprinkle with remaining sugar
Transfer to a baking sheet lined with parchment paper.
Bake at 400 degrees. My recipe said 14 -16 but that did not seem like enough time. I think it was at least 20 before I thought they were done.