Cut the broccoli into florets. Skin the stem and dice the core. Rinse well.
Boil about half a gallon of water in a pot with a tablespoon of salt.
When the water is boiling profusely, drop in the diced broccoli stem and leave for a minute. Do not lower the heat.
Add the florets to the diced stem and leave in the boiling water for another minute.
Drain the broccoli in a strainer. Bathe in cold water under the tap until cool or plunge in a bowl of iced water. Drain completely.
Make the dressing by mixing all the ingredients together until smooth.
Transfer the drained broccoli to a platter or bowl, drizzle in the dressing and sprinkle with sesame seeds.
For those who like more dressing, serve the remaining dressing on the side.