This recipe works best with firm orange-skinned pumpkins, such as 'Cheese' or 'Small Sugar Pie.'
Cut the pumpkin into wedges about 3 to 4 inches wide. Cut across wedges to form slices about 1/4 inch wide; set aside.
Combine 2 cups sugar, lemon juice, and zest in a medium bowl. Add pumpkin pieces; stir until well coated. Cover with plastic wrap; refrigerate overnight.
Transfer mixture to a medium heavy-bottomed saucepan; bring to a simmer over medium heat. Reduce heat to medium-low; cook, stirring occasionally, until pumpkin is translucent and sugar has formed a light-amber-colored caramel, 1 hour 10 minutes to 1 hour 15 minutes.
Remove pumpkin from caramel with a slotted spoon, and dry on a rack set over a cookie sheet for at least 12 hours, turning the pumpkin pieces once or twice.