A note about the method: A food processor is needed to make your own walnut flour. You can buy walnut flour- it's just hard to find in stores. A food processor also helps to really incorporate the ingredients and seems to result in a fluffier, more "bread-like" bun. This recipe CAN be made without a food processor. Simply add ingredients to a mixing bowl with walnut flour or substitute almond flour. I have found that the mixing bowl method still results in a tasty bun, it's just less fluffy than if a food processor is used.