Pour the warm water into a large bowl and sprinkle with the yeast. Stir and set aside for 5 minutes. Add the brown sugar, salt, and 2 cups of the flour and beat with a wooden spoon for 100 strokes. Set this “sponge” aside for 5 minutes. Stir in enough of the remaining flour, about 1⁄3 cup at a time, to make a firm dough.
Turn the dough out onto a floured work surface and knead for 6 to 7 minutes, until smooth, supple, and elastic.
Oil a large bowl, add the dough, and rotate it to coat the entire surface. Cover the bowl with plastic wrap and set aside in a warm, draft-free spot until the dough is doubled in bulk, about 45 to 60 minutes.
Preheat the oven to 425°F.
Lightly coat two large baking sheets with shortening or oil, but not butter.
Punch down the dough and turn it out onto a lightly floured work surface. Knead for 2 minutes. Divide the dough in half and put one half in the bowl and cover it. Divide the remaining half into three equal pieces. Shape into balls and let rest for 2 to 3 minutes. Working with one piece at a time, roll the dough to make a rope 30 inches long. Shape the rope into a large horseshoe, with the ends pointed away. Holding the ends, cross them about 4 inches from each end, forming a large circle. Twist the ends together once (as you would twist a wire bread tie), pull them toward you, and drape them over opposite sides of the circle to form the classic pretzel shape. Place the pretzel on the baking sheet. Repeat for the other two dough balls, leaving plenty of space between them on the baking sheet.
Combine the hot water and sugar in a small bowl, stir, and lightly brush it on the pretzels. Sprinkle with coarse salt, if desired. Let rest for 10 minutes.
Bake on the center oven rack for 12 to 15 minutes, or until golden brown.
Briefly knead the remaining dough. Shape three more pretzels and place them on the second baking sheet.
Transfer the first batch to a cooling rack and immediately brush with the melted butter several times.
Bake the second batch as directed. Serve warm.
Cinnamon Sugar Pretzels: Brush each pretzel with hot water, then sprinkle liberally with cinnamon sugar (3 tablespoons of sugar mixed with ¼ teaspoon of cinnamon).
Bake and butter, as directed.
Pizza Pretzels: Brush each pretzel with hot water, then spread 1 tablespoon of sun-dried tomato pesto on each one. (Store-bought pesto is fine.)
Bake and butter as directed.
Sprinkle generously with grated Parmesan cheese while still hot.