Fresh yeast is available at bagel bakeries or any bakery - just ask for a block. Instant dry yeast is also perfectly fine for this feathery, moist and lightly sweet holiday challah but nothing beats the imcomparable taste and texture of a challah made with fresh yeast, let alone, the fragrance! If you never experienced the slightly different (and more subtle) scent of fresh yeast in home bread baking, make this new year the time to start. Be brave. Be bold. Start the new year on a high note.