Bring a big pot of water to a boil, then season the water well with salt. Also set up a big bowl of ice water. Drop in your broccoli florets, and blanch for about 60 to 90 seconds. Take a piece of broccoli out and taste it, to make sure it's to your liking (it should be crisp, but with the raw edge taken off). Immediately remove the broccoli from the boiling water and shock it in the ice water for 15 seconds. Drain the broccoli, then dry well with paper towels.
Whisk to combine the rice vinegar, honey, soy sauce, sesame oil, sesame seeds, ginger, red pepper flakes, and scallions.