Scoop the seeds and stringy pulp from the pumpkin into a large bowl of water. Rub them between your fingers; the seeds float and the pulp sinks. Skim off the seeds and discard the pulp.
Optional: boil the seeds in 4 cups of water with 1 tablespoon of salt for 10 minutes, then drain.
Spread the seeds on a clean kitchen towel and pat them thoroughly dry. Let them air-dry for 15 minutes if you have time.
Heat the oven to 325°F (165°C). Toss the seeds with the oil, salt and your choice of savory or sweet seasonings.
Spread them in a single layer on a parchment-lined baking sheet and roast for 15–25 minutes, stirring every 5 minutes, until golden and crisp.
Let them cool completely on the pan; they continue to crisp as they cool.