Mixing the dough: In a 6 quart bowl combine starter, water, oil, eggs, 1/2 of the flour, Stevia, and vital wheat gluten. Mix well until the ingredients are well combined (I use a Danish Dough Whisk) . Add remaining flour and salt. Mix well. Cover the bowl and allow it to ferment for 1 hour. Remove the lid and do one set of stretch and folds. Do 3 more sets of stretch and folds within the next 4 hours. After the dough has fermented for 5 hours counting from the time you mixed it, it is ready to shape. Shaping the dough: Prepare a baking sheet by laying a piece of parchment paper on it. Divide the challah dough into 4 equal pieces. Lay one dough piece aside. Take the remaining 3 dough pieces and roll each piece into an 18 inch rope. Braid the 3 ropes together, tucking the ends under. Place the braided loaf on the baking sheet. Take the remaining piece of challah dough and divide it into 3 pieces. Roll each piece into a 12 inch rope. Braid the 3 pieces together. Lay the smaller braid on top of the larger bread. Cover the challah loaf with well greased plastic wrap. Allow the loaf to proof for 1.5-2 hours. Baking: Preheat your oven to 350 degrees F. Beat the egg white and water until frothy. Brush the loaf with the egg wash making sure cover the entire surface. If desired you can sprinkle the loaf with the seeds of your choice. Bake for 30-32 minutes or until bread reaches an internal temp of 210 F. Remove challah from the oven and cool on a wire rack. 1 challah loaf--18 slices.