Single-acting baking powder first hit the marketplace in the mid-1850's. The Gold Rush was still rushing, and John Chisum's cattle drives were at their peak, repleat with chuck wagon and cook--always called "Cookie" regardless his origins. Sourdough was a critical supply (ref.: http://www.articlesnatch.com/Article/Contents-Of-A-Chuck-Wagon-Cooking-Supply-List/1621894 ) Baking powder isn't mentioned. Double acting baking powder, began replacing single-acting in the early 1890's, just in time for the Yukon Gold Rush.
So why don't we hear stories about the buckaroo that rode three days straight to the nearest town, crossing miles of desert, evading irate Indians, or roaming banditos just to replace Cookie's Rumford Baking Powder, 'cause he forgot to pack extree? How come we don't quote Robert Service's poem about the cook who was "strung up" by his fellow miners, when he forgot to pack 10 lbs. of baking powder in their supplies? (ref.: http://www.questconnect.org/ak_chilkoot_supplies.htm )
We don't. But our history of rough times and places is peppered with sourdough stories. My favorite is about the frozen miner's corpse found curled around his starter. The miners that found him quickly baked up a batch of Dutch Oven biscuits to make sure his starter hadn't shared his fate. While they sipped coffee, and munched biscuits, the conversation at last got around to what to do with the body. (OK, I just made that up.)
Yesterday, I dutifully fed my starters their weekly ration. I had about 200g of discard starter. The night before, I'd watched True Grit (the real one, with John Wayne) so I was in the mood for some real sourdugh biscuits. As ever, I googled recipes.
Much to my disappointment the first half-a-million recipes I scanned all called for baking powder--from a tsp. to 2 Tbls. Sourdough starter seemed to be almost an afterthought.--1/4 cup to 2 cups. None of them required refreshing. Just stir the starter in, and rely on the baking powder to puff them up. In the second half-a-million recipes--ain't Google grand?--I found one recipe wherein baking powder was optional, but recommended it if you didn't want to wait.
Here's what I did.
356g (12.5 oz.; 2 cups) sourdough starter; 100% hydration; refreshed 12 hours earlier, and left to develop at 76°F
76g (2.7 oz.; 1/3 cup) 50/50 mixture butter and lard (yep, lard: probably Cookie's first (only?) choice). Cut in to 1/2" cubes and chilled in the freezer for 15 minutes
300g (10.6 oz; 2-1/2 cups) AP flour
14g (1 tbls) sugar
7g (1 tsp) salt
I mixed the flour, sugar, salt, and butter/lard cubes together with my hand, squeezing the fat cubes between my thumb and fingers until they were all flattened and well coated with flour. I added the sourdough starter, mixed it in, and kneaded the dough in the bowl, until it formed a ball. The dough felt a little dry, but I didn't add any additional liquid.
I rested the dough, covered and chilled in the refrigerator, for 15 minutes.
I turned the ball out onto an unfloured dough board, and rolled it to about 1 inch thick, folded the dough in half, and rolled it out again. I repeated this about six times. Each time I rolled it out the dough got more flexible, and felt less dry. I was glad I hadn't added additonal liquid.
On the final roll-out I went to 1/2 inch thick, cut out 17, 2-1/4" biscuits, arranged them on a Silpat pad lined half-sheet pan, covered them with a dry tea towel, and returned them to the proofing box (76°F).
They proofed for 2 and 1/2 hours. They had expanded, but not doubled.
Baked in a 400°F oven for 14 minutes (light golden brown). They more than doubled with oven spring. Lifting the first one to the cooling rack I knew, from its light feel, I had a success.
The crumb is closed, but not dense; looks like most other baking powder biscuits I've made. However, flavor-wise it is definately sourdough! I ate one cold, with nothing added this AM. Firm mouthfeel, and a lovely tang in the after taste.
I think I overworked the dough a little. Next time--and there will be a next time--I'll only roll them out three or four folds. I will also up the temp to 425°F, and bake them on my baking stone.
I think this is more like what Cookie baked.