Slice the asparagus in a long diagonal at 2" intervals. Blanch in a large pot of boiling water for about 4 minutes, until just tender-crunchy. Drain, refresh under cold running water, then dry carefully with paper towels.
Whisk together the rice wine vinegar, soy sauce, sugar, red pepper, corn oil, sesame seed oil and salt, to taste. Toss with the asparagus. Cool, cover and refrigerate for several hours or overnight, if desired.
Melt the butter in a small saute pan and stir-fry the sunflower seeds until golden brown. Remove and reserve.
When ready to serve, toss the asparagus and vinaigrette again, arrange on red lettuce leaves on individual salad plates and top with toasted sunflower seeds and sliced green onions.