If you use a stand mixer, yes, you must use the dough hook. While the Tsoureki dough is on the softer side, it is still a heavy mixture for a mixer, and a paddle or whisk attachment won’t work. I do suggest using a stand mixer with a dough hook for this recipe if you have one. The mixer does all the hard work of mixing and kneading, which is especially helpful with enriched bread recipes like this one that start out much softer and stickier. If you don’t have a stand mixer or a dough hook, you can start the process by stirring the dough together with a wooden spoon and then kneading it with your hands on a lightly floured surface.