Bring large pot of water to a boil. Cut wing beans lengthwise and then cut in half.
Blanch beans in boiling water for 3-4 minutes until crisp tender. Shock in ice water or run under cold water. Drain well.
Mix dressing ingredients together in a bowl. Toss with drained beans and chopped egg. Reserve some chopped hardboiled egg for garnish on top.
Notes
If you can't find winged beans, regular green beans work well too.
To make this vegetarian, substitute fish sauce with 1/2 Tb soy sauce and additional salt to taste. Also, leave the egg garnish for the top, so the soy sauce doesn't make it brown.
Other items you could add are poached shrimp, cooked ground pork, fried shallots, grapefruit segments, or fried garlic chips.
To make ahead of time, complete all steps but mix the dressing with the beans when ready to serve.