Hydrate the yeast. Mix yeast packet with the warm water and sugar, and let the foam double in size.
Make the brioche dough. Mix the flour, sugar, water, activated yeast, lemon zest, salt and eggs into the bowl of an electric mixer with a dough hook attachment and mix on medium speed for 1-2 minutes, until it's all combined. Then turn up the speed to medium high and let it run for about 5 minutes, or until the dough starts coming away from the sides and forms a ball. Turn off the mixer and let the dough rest for a minute. Slowly add the butter to the dough, about 25g at a time. Once it is all incorporated, mix on high speed for 5min until the dough is glossy, smooth and very elastic when pulled.
Proof the dough. Cover the bowl with saran wrap and leave to proof in the bowl until it has doubled in size - about 1-2 hours. Punch down the dough – then re-cover the bowl and put into the fridge to chill overnight. The next day, take the dough out of the fridge and shape into whatever brioche style you're going to bake/fry/eat. Cover lightly with Saran wrap and leave out in a 75F room for about 3hr, or until about doubled in size, then bake or fry according to that recipe's instructions.
I've included volume ingredients here but BAKING TURNS OUT BETTER WHEN YOU MEASURE IN WEIGHT