Combine the rinsed split peas and water in a medium bowl or other container; loosely cover. Let stand, at room temperature, for at least 6 hours or up to 12 hours.
Do not drain split peas.
Add the entire contents of bowl (soaked peas and remaining water) and optional salt to a blender. Blend on HIGH speed until completely smooth (no tiny bumps) stopping multiple times to scrape down the sides of container (it will take 2 to 3 minutes). The batter should be very smooth. Scrape into a bowl or measuring cup.
Heat a nonstick skillet (or very well-seasoned cast iron skillet that is nonstick), or a nonstick griddle, to medium heat (no hotter).
Once warm, reduce heat to LOW. Add ⅓ cup of batter to the center of the pan. Using a metal spoon, spread the batter into a 6-inch (15 cm) circle.
Cook 2 to 3 minutes until surface of tortilla appears dry. Slide a spatula underneath and flip. Cook about 1 minute longer to brown other side. Transfer to cooling rack and cool completely.
Repeat with the remaining batter.
