Sourdough Pancakes

Didn't post this recipe before, I think-- just referenced Sandor Katz, whose recipe it is. But I've eaten enough now that I consider it my recipe too.

This makes enough pancakes for two people (if those people are Kate and me).

Mix together and rest overnight:
1/2 cup sourdough starter
1 cup lukewarm water, or half water, half milk
1 Tablespoon sweetener (syrup? barley malt?)
1 1/4 cups white flour

In the morning, melt
1 Tablespoon butter

and beat in
1 egg yolk
1/2 teaspoon salt

In a separate bowl, beat the egg white until stiff, mix it into the butter and yolk, and fold everything into the sourdough until just combined. Scoop the batter by quarter-cups into a well-seasoned, hot pan and cook two minutes or so on each side. If you like, sprinkle blueberries into the batter just after pouring it into the pan. Serve hot, with butter and maple syrup.