I have never had the patience for sour dough starter, so I have used the improvised version of it -- I think this is the brand that I've used, but not 100 percent certain. It's not better than the real thing but it's as good.
Sour Dough Bread Enhancer
My favorite bread machine recipe -- other than the sweet breads
English Muffin Bread
1 and a splash cup warm water
2 tsp sugar
1 tspsalt
1/4 tsp baking soda
3 cups bread flour -- white (1/2 white 1/2 wheat also works too)
3 tsp nonfat dry milk
2 tsp active dry yeast
Put all ingredients in machine in the order suggested by your machine's manufacturer and set to regular bread or fast cycles.
The top of the loaf should come out sunken, this is normal. The texture and taste is just like English Muffins, this is GREAT for toasting!