Place water and sugar in large mixing bowl. Sprinkle with yeast - allow to proof for 2-3 minutes. If you do not see activity (foaming), toss the yeast and start again.
To the mixture in the bowl, add the pumpkin puree, salt and 2 C. of the flour. Mix gently with your hands. Slowly add in the last remaining cup of flour.
Reach into the bowl and mix with your hands until it all comes together. It will be very sticky. Continue to mix until the dough is smooth and elastic. (Alternatively, you can use your mixer with the bread dough attachment).
Tidy the dough into a ball. Cover the bowl and allow to rise for 12-13 hours until the dough has risen more than doubled and bubbles have formed on the top of the surface.
Remove the dough from the surface, place on a clean countertop dusted with a little flour.
Grab the side of the dough farthest away from you, and stretch up (3x the height of the dough), and fold over the dough. Repeat on the right side of the dough, then the left. Then flip the ball of dough over, the smooth side should be on top. Cup your hands around the ball of dough and rotate until the dough resembles a smooth ball.
Place a piece of parchment on top of your flat counter surface. Place the ball of dough on the parchment.
Gently cover with a clean, damp linen rag and allow to rise an additional hour.
About halfway through the second rise, turn your oven on 450 degrees F. Place your Dutch oven (with lid) in the oven and allow it to get hot - anywhere from 30-45 min.