Combine yeast, hot water, and sugar in a bowl and let sit 5 minutes.
Add in cauliflower, margarine, molasses, and mustard. Add in 2 cups all-purpose flour, rye flour, salt, 1 teaspoon caraway seeds, 1 teaspoon fennel seeds, and dill weed. Add in enough flour to form a smooth dough.
Knead dough until elastic, about 5 minutes.
Lay dough in a greased bowl and let rise, covered in a warm place 1 hour, dough should be doubled in size. Punch down dough.
Form dough into a loaf. Lay loaf in a greased 9 x 5 inch loaf pan. Let rest, covered, 45 to 60 minutes or until doubled in size.
Preheat oven to 350 degrees F.
Slice slits into top of dough and coat with egg whites. Top with the rest of the caraway and fennel seeds. Bake for 40 to 50 minutes. Let cool before slicing.