Cut the top off the pumpkin, then scoop out the insides using a pumpkin cleaning tool. Scrape away all the strings and seeds from the walls and place everything, the pulp and seeds, into a large bowl or pot.
Fill the bowl with water and stir to separate the seeds from the pulp. The seeds will float while the strings sink. Pour the floating seeds into a colander, leaving behind most of the pulp and strings.
Rinse the seeds under running water, removing any leftover pumpkin pieces. Refill the bowl with clean water, and scoop out the floating seeds once more to ensure they’re fully cleaned and ready for soaking.
Dissolve ½ cup of sea salt in 4 cups of warm water. Soak the seeds for 1–3 hours, then drain. Spread them on a baking sheet, sprinkle with salt, and bake at 350°F for 20–30 minutes, flipping occasionally until dry.