In stand mixer bowl, combine 1 cup bread flour, yeast, sugar, fennel seeds, caraway seeds, and salt. Add warm water and oil to flour mixture. Using a paddle attachment, blend on low speed for 30 seconds. Beat on medium speed for 4 minutes.
Switch to dough hook attachment. Gradually stir in rye flour and enough remaining flour to make a firm dough. Knead until smooth and elastic, about 5 to 7 minutes.(NOTE: For hand mixing: following above steps, mix ingredients in large mixing bowl using a wooden spoon or dough whisk. Knead on floured surface until smooth and elastic.) Place dough in lightly oiled bowl and turn to grease top. Cover; let rise until indentation remains after poking dough with finger down to second knuckle, about 1 hour.
Turn dough onto lightly floured surface; punch down to remove air bubbles. Shape into round loaf. Place on lightly greased cookie sheet. Cover; let rise in warm place until indentation remains after touching.
Preheat oven to 375°F.
If desired, slash top 2 or 3 times with very sharp knife in a decorative pattern and brush with slightly beaten egg white. Bake for 40 to 45 minutes until the loaf sounds hollow when tapped. Remove from pan; cool before slicing.