For convenience, look for a 12-oz. package of sliced salt pork from Hormel. You'll need three slices.
Place peas in a Dutch oven; cover with cold water 2 inches above peas. Bring to a boil; boil 1 minute. Cover, remove from heat, and let stand 1 hour. Drain peas, and rinse thoroughly.
Bring salt pork and 1 qt. water to a boil in Dutch oven over medium-high heat; reduce heat to medium-low, and simmer 30 minutes. Add peas, onion, next 2 ingredients, water to cover, and, if desired, jalapeño pepper. Bring to a boil over medium-high heat. Cover, reduce heat, and cook, stirring occasionally, 1 hour to 1 hour and 30 minutes or until peas are tender and liquid thickens slightly. (Uncover after 1 hour to allow liquid to evaporate, if necessary.) Season with salt and pepper to taste.