Recently a friend offered us a tablespoon of her sourdough starter. And we came to discover that baking bread and marriage have some surprising similarities. The Process Karen: I knew that accepting this little bit of sourdough starter came with a lot of responsibility. It would need to be fed on a regular basis and provided a warm environment in which to grow. We would have to observe this dough using all our senses. Does it look frothy and bubbly… feel stretchy… smell just the right amount of yeasty? On occasion we would need to discard some of the starter before feeding to keep it from becoming too sour. It…