In a mixing bowl, DISSOLVE yeast and sugar in warm water; let STAND for five minutes.

ADD the oil, 1/8 teaspoon salt and two cups flour; BEAT until smooth.

STIR in enough remaining flour to form a soft dough.

TURN onto a floured surface; KNEAD until smooth and elastic, about five minutes.

PLACE in a greased bowl, TURNING once to grease top; COVER; let RISE in a warm place until doubled, about one hour.

Meanwhile, in a skillet, COOK sausage and onion over medium heat until meat is no longer pink; DRAIN.

ADD tomato sauce, green pepper, garlic, Italian seasoning, pepper and salt; SET aside.

PUNCH dough down; on a large greased baking sheet, ROLL dough into an 18 x 12-in oval.

SPREAD sausage mixture lengthwise down the center.

COMBINE the sour cream and cream cheese; SPREAD over sausage mixture; SPRINKLE with shredded mozzarella.

FOLD one long side of dough over filling; FOLD other long side over the top; PINCH seam and ends to seal.

With a sharp knife, cut slits in top of dough; COVER; let RISE until doubled, about 30 minutes.

BRUSH to with egg white; SPRINKLE with fennel seed.

BAKE at 400F until lightly browned, about 25-30 minutes.

Let stand for ten minutes before slicing.