Rinse peas, cut off stem end and string, if necessary.
Pour about 3/4 inch water into a large skillet and bring to a boil over moderate heat.
Add peas, cover, and boil gently for 3 to 4 minutes, or until tender, tossing with a spatula once or twice.
If water evaporates before peas are tender, reduce heat and add more water.
Drain any remaining water.
Add oil, if using, and salt to taste and toss to coat.
(Peas may be refrigerated overnight.
Reheat, covered, in a microwave for 2 to 4 minutes or until hot, stirring once.)