Thinly slice green onions, keeping green tops separate from white bottoms; set aside. Cook edamame according to package directions, except omit salt; drain. Rinse with cold water; drain again. Reserve a few edamame for garnish.
In a food processor, combine white parts of green onions, the remaining cooked edamame, parsley, the water, lemon juice, lemongrass, oil, garlic, ginger, and salt, Cover and process until nearly smooth. Stir in green onion tops.
Transfer mixture to a serving bowl. Garnish with the reserved edamame and, if desired, crushed red pepper. Serve with vegetable dippers.
Prepare as directed, except cover and store in the refrigerator for up to 24 hours.