Here is a recipe in case you want to try making it in the UK.

Sourdough Bread - San Francisco Style

Ingredients

* 4 3/4 cups bread flour
* 3 tablespoons white sugar
* 2 1/2 teaspoons salt
* 1 (.25 ounce) package active dry yeast
* 1 cup warm milk
* 2 tablespoons margarine, softened
* 1 1/2 cups sourdough starter
* 1 extra large egg
* 1 tablespoon water
* 1/4 cup chopped onion

Directions

1. In a large bowl, combine 1 cup flour, sugar, salt, and dry yeast. Add milk and softened butter or margarine. Stir in starter. Mix in up to 3 3/4 cups flour gradually, you may need more depending on your climate.
2. Turn dough out onto a floured surface, and knead for 8 to 10 minutes. Place in a greased bowl, turn once to oil surface, and cover. Allow to rise for 1 hour, or until doubled in volume.
3. Punch down, and let rest 15 minutes. Shape into loaves. Place on a greased baking pan. Allow to rise for 1 hour, or until doubled.
4. Brush egg wash over tops of loaves, and sprinkle with chopped onion.
5. Bake at 375 degrees F (190 degrees C) for 30 minutes, or till done.