Dissolve the yeast in the warm water in a small bowl or cup. Let sit for a few minutes.
Combine flour, powdered sugar and salt in a large mixing bowl. Add water with yeast and vegetable oil. Stir with a spoon and then use your hands to form dough into a ball. Knead the dough for 5 minutes on a lightly floured surface. (Dough will be nice and smooth when ready). Place the dough into a lightly oiled bowl, cover it, store in a warm place for about 45 minutes or until dough rises to double in size.
When dough has risen, preheat oven to 425°F.
Make a bath for the pretzels by combining the baking soda with the warm water and stir until baking soda is mostly dissolved.
Remove the dough from the bowl and divide it into 8 even portions. Roll each portion on a flat non-floured surface until it is about 3 ft long. Pick up both ends of the dough and give it a little spin so the middle of the dough spins around once. Lay the dough down with the loop nearest to you. Fold the ends down toward you and pinch to attach them to the bottom of the loop. The twist should be in the middle.
Holding the pinched ends, dip each pretzel into the bath solution. Put each pretzel on a paper towel for a moment to blot the excess liquid. Arrange the pretzels on a baking sheet sprayed with non-stick spray. If you want salt, sprinkle pretzels with kosher salt or pretzel salt. DON'T salt any pretzels you plan to coat with cinnamon sugar. You will likely have to use two baking sheets and bake them separately. Bake the pretzels for 4 minutes and then spin the pan around and bake for another 4-5 minutes or until the pretzels are golden brown.
Remove the pretzels from the oven and let them cool for a couple of minutes. If you want to eat some now, brush them with melted butter first before serving.
If you want the cinnamon sugar coating, make it by combining the 1/2 cup sugar and 2 teaspoons cinnamon in a small bowl. Brush the unsalted pretzels with melted butter. Sprinkle a heavy coating of the cinnamon sugar on the pretzels over a large plate.