Yields 1 loaf
2 tablespoons butter
In a small skillet, melt the butter and saute onion and celery until soft, sprinklds with a little salt and pepper to bring out the flavor, about 5 minutes. Remove from heat and set aside to cool.
In a large mixing bowl, whisk together the flour, yeast, onion powder, thyme, sage, parsley, and celery seeds if using. In a large measuring cup, lightly beat the egg. Add the boullion granules and warm water, and mix well with a fork to dissolve the boullion. Add mixture to the dry ingredfients and mix until the dough begins to form. Add the cooked vegetables and knead 6-8 minutes. The dough will seem dry as first, but should become smooth and supple as the vegetables give up their liquid. Adjust flour or water, a teaspoon as a time if needed. Place dough in a lightly oiled bowl. Cover with plastic wrap and allow to rise until doubled, about 1 hour.
Deflate the dough, turn it out onto a lightly oiled surface and form into a loaf. Place in a lightly oiled 8x4 loaf pan, cover with lightly oiled plastic wrap and let rise until it domes an inch above the rim of the pan, about 40-45 minutes.
Preheat oven to 375 degrees F. Slash the top of the dough down the center. Bake 35-40 minutes until golden brown and internal temperature on an instant-read thermometer registers 190 degrees F.
Remove from the oven, turn it out of the pan, and cool completely on a rack before slicing.