When I have made sourdough boules (such as Whole Wheat Sourdough Boule ) I have a lot of starter which is discarded on the morning of the second day, which seems wasteful.  I decided to use it as the base of a flatbread for breakfast.  The starter is 100% hydrated (i.e. equal weights of flour and water) which is too wet even for a flatbread.  I therefore weighed the discard (350 g. this morning) and added enough bread flour to bring it down to 77% hydration, the same as one of my pizza dough recipes.  (Thus the weight of the water became 77% of the weight of the flour.  In this case I added 52 g. of flour.)  Add table salt equal to 2% of the weight of the flour.  (In this case there was about 228 g. of flour, so I added 5 g. of table salt.)  Mix in some diced sausage.  (This morning, I chopped up one link of kielbasa weighing about 83 g.)  Mix with a dough whisk until smooth and then put on a sheet of baking parchment.  Flour the top surface and press and spread the dough until it is about ½ inch thick and about 10 inches in diameter.  Cover and allow it rest for about 30 minutes while heating the oven and a pizza steel at 475 degrees.  Bake about 14 minutes until golden.  Cut into pieces and serve.