Set starter out about 1 hour prior to mixing final dough.
In the bowl of a stand mixer fitted with a flat beater, combine water and firm starter.
Mix on medium low speed until combined, about 3-4 minutes.
Add pumpkin and barley malt.
Mix until combined, about 1-2 minutes.
Switch to dough hook.
Add flour.
Mix on low speed until combined, about 1-2 minutes.
Increase speed to medium high.
Knead for 5 minutes.
Add salt.
Knead until dough is smooth and elastic, about 5 more minutes.
Place in a covered container, or in a bowl in a proofing box.
Allow dough to rise until doubled in bulk, about 4 hours. In a proofing box, set temperature to 80℉.
While dough is proofing, line a 9 inch banneton with a liner or tea towel.
Dust with rice flour.
Turn dough out onto a lightly floured surface.
Use a bench knife, or you hands (either floured or wet) to round the dough and pull it tight.
Place dough upside down in prepared banneton.
Cover with a disposable shower cap, or plastic wrap.
Place in refrigerator overnight.
At least 1 hour before you are ready to bake, place Dutch oven on middle shelf of oven, and heat oven to 375℉.
When ready to bake, cut 4 pieces of kitchen twine, each 24 inches long.
Soak pieces of twine in vegetable oil.
Draw your fingers along each string to squeeze out excess oil.
Place strings in a starburst pattern on a piece of parchment paper.
Turn dough out onto strings with the center on the dough lining up with the center of the strings.
Tie the strings over the dough, dividing it into eighths.
Snip off the excess string.
Use a lame, or razor blade, to make slashes about ¼ inch deep in dough in desired pattern.
Lift bread by parchment and set it into Dutch oven.
Cover.
Bake for 20 minutes.
Remove lid.
Bake for an additional 30-35 minutes, until bread is golden and tests done.
Carefully remove bread from Dutch oven.
Snip and remove the strings.