In a 12- inch non-stick skillet, heat oil on low medium heat 1 minute. Add onion and cook about 20 minutes or until very tender and golden brown, stirring occasionally.
Stir in peas, salt and pepper; cook 3 minutes longer until peas are cooked. Remove skillet from heat.
Grate 1 teaspoon of lemon zest, add to a small bowl with 2 tablespoons lemon juice. Stir in mayonnaise and curry powder.
Place chopped eggs in a large bowl, add onion mixture, mayo mixture, celery, and parsley; stir gently with a rubber spatula to combine. If you like, cover and refrigerate 1 hour or until chilled.
To serve, place greens on 4 dinner plates, top with egg salad and sprinkle with chopped walnuts. Enjoy!