In a mixer bowl and with a dough hook, add the hot water, yeast, sugar and lemon juice and let sit for 5 minutes. Once the mixture is bubbly, add the flour one cup at a time as well as the salt. Knead the dough for 5 minutes until the dough starts to pull away from the edge of the bowl. Cover the bowl with a towel and let rest until doubled in size (about 1 hour).
Preheat your oven to 500°F. Prepare two baking sheets by lining them with parchment paper or lightly greasing them.
Transfer the dough to a lightly greased work surface, and divide it into eight strips of equal length. Allow the pieces to rest, uncovered, for 5 minutes. While the dough is resting, combine the 1/2 cup warm water and the baking soda in a liquid measuring cup (deep enough to dip the pretzel bites into). Make sure the baking soda is thoroughly dissolved.
Cut each strip of dough into 6-8 pieces, about 1 to 1 ½ inches in width. You don’t have to be completely exact, just eyeball it. Dip each pretzel bite in the baking soda solution (this will give the pretzels a nice, golden-brown color), and place them on the baking sheets. Sprinkle them lightly with coarse, kosher, or pretzel salt. Allow them to rest, uncovered, for 10 minutes. Bake the pretzels for 7-8 minutes or until they’re golden brown. Bake one sheet at a time. Remove the pretzels from the oven, and brush them thoroughly with the melted butter.