Rinse the cauliflower well, trim and cut into florets.
In a large mixing bowl, stir together the flour and starch with the salt and pepper.
Pour in iced water little by little, mixing as you pour, until you have a thick but still pourable batter.
In a frying pan or wok, heat enough cooking oil to reach a depth of at least three inches.
Dump the cauliflower florets into the batter and mix lightly but thoroughly to coat each floret with batter.
Drop the batter-coated florets one by one into the hot oil.
Cook over medium-high heat, turning them over midway through the cooking, until crispy and lightly browned.
Scoop out the florets and spread on a rack.
Pour off the oil from the pan.
Add all the ingredients for the Buffalo sauce and half of the sesame seeds into the pan.
Cook over medium heat, stirring often, until the mixture reaches boiling point. Turn off the heat.
Add the cauliflower florets to the sauce and toss to coat all of them well.
Transfer the crispy Buffalo cauliflower florets to a plate (or plates if you want to serve them individually like I did) and sprinkle with the remaining toasted sesame seeds. Optionally, sprinkle in some chopped parsley too.
Serve the crispy Buffalo cauliflower florets at once.