Gluten-free citrus and pistachio roll

Boil the milk with the butter.
Pour over the egg yolks, beaten with sugar,
corn starch and buckwheat flour.
Thicken without boiling, on the heat, whisking
GOOD.
Beat the egg whites with the second part
of sugar.
Mix the two masses while whisking
quickly and spread on a covered plate
of parchment paper. Bake for 15 minutes at
170°C.
Turn the sheet over and let it cool.

Zest the citrus fruits and blanch twice in
lightly salted water. Drain.
Roughly chop the citrus pulp.
Mix with the blanched zest and add the
sugar and water.
Cook for 20 minutes at a low boil with the
scraped vanilla.
Add the pectin in a rain mixed with a
little sugar. Boil for 30 seconds in
mixing well.
Mix and chill.