1) Combine all of the dough ingredients in a large mixing bowl and stir to form a cohesive dough.
2) Knead the dough, by hand, mixer, or bread machine, for 5 to 8 minutes, until it's smooth, soft and supple; avoid adding too much flour, as this will make the buns tough and dry. If you're using a stand mixer, knead for 2 minutes with the flat beater, then switch to the dough hook and knead for an additional 5 minutes.
3) Place the dough in a lightly greased bowl, cover the bowl with plastic wrap, and allow the dough to rise for about 1 1/2 hours, or until it's puffy, though it probably won't have doubled in bulk.
4) Transfer the dough to a lightly oiled work surface, and divide it into 16 pieces (about 1 1/2 ounces or 43g each).
5) To make round buns, simply round the pieces into balls. To make hearts or knots, see our illustrated blog post for complete instructions.
6) For soft-sided round buns, place them in a lightly greased 9" x 13" pan. For knots or hearts, space the shaped buns on two lightly greased or parchment-lined baking sheets.
7) Cover the buns, and allow them to rise for about 1 1/2 hours, or until they're nice and puffy; when you press a finger gently into a bun, the resulting indentation shouldn't spring back.
8) While the buns are rising, combine the egg white and water, and set aside. Preheat the oven to 350°F.
9) Brush the risen buns with the egg white mixture, and sprinkle with coarse or pearl sugar.
10) Bake the buns for 20 minutes, or until they're a light golden brown. Remove the buns from the oven, and transfer them to a rack to cool. Serve warm, or store in an airtight container (a plastic bag is fine) until ready to serve.