Mix the 4 cups of flour, 1/4 cup pumpkin powder (if using), and 2 tsp. sea salt in a medium sized bowl.
In a separate bowl, mix the 1 1/2 cups water, 2 Tbsp. honey, and 1/2 cup sourdough starter thoroughly.
Add the water mixture to the flour mixture and mix until incorporated. If using a stand mixer, dough should clear the sides of the bowl when using a dough hook. If mixing by hand, the dough will become uniform and form a ball.
Cover and set aside in a warm place for at least six hours to ferment.
Mix the 1/2 cup of sugar with the 1 Tbsp. of spice.
After at least six hours, remove the dough from the bowl and wet a clean countertop to roll the dough into a rectangle. Sprinkle half the sugar mixture evenly over the surface of the dough.
Fold the dough in half over itself, and then in half again to make a fat rectangle. Flatten this out as you did before. You will encounter more resistance this second time since all your work with the dough will activate the gluten in the flour. Be gentle, but be firm.
Once you've flattened the rectangle again, sprinkle the remaining sugar mixture over the dough. Fold in half, and in half again. Flatten the dough to a rectangle again. Be gentle, but firm. You won't produce as wide a rectangle this time, so just do your best.
Orient the rectangle of dough so that its length is horizontal. Using kitchen scissors, cut eight strips of dough. You can measure or simply eyeball it.
Pick up each strip and shape into the classic bagel shape by forming a circle with the dough strip and pressing the ends together, slightly tucking them under. Again, be gentle but firm. You're the boss, so be sure the bagel is the shape you want - round with a hole in the middle. See the notes section for more help.
Place each bagel on a baking sheet lined with parchment paper and cover* to rise for 2-3 hours, or until doubled in size.
When the bagels are ready, bring 2 quarts of water to a boil and gently place 3-4 bagels in the boiling water. Allow them to boil on each side for 1/2 minutes. Remove them one by one and place on a greased bakers rack to drain.
Repeat with the remaining bagels and allow to drain completely.
Place the boiled bagels on a parchment lined baking sheet and bake for 30 minutes or until slightly browned. You should be able to smell the bagels wafting through the house when they're just about done.
Allow to cool completely, if you can manage to wait that long. If you cut into bread before it sets up completely, it can get gummy. However, you don't need my permission to tear into your hot bagels, melt butter all over them, and eat them up for dessert tonight.