Fill half of a large bowl with ice.

Bring a saucepan of water to a simmer. Take a medium stainless-steel mixing bowl that can fit over it and not touch the water or you will have scrambled eggs!

Add yolks, champagne or wine, sugar, vanilla, lemon juice, and zest to a medium stainless-steel bowl, whisk to mix. Rest the bowl in the saucepan over hot water. Whisk constantly for 5 minutes or more to cook the sauce, until it has the consistency of lightly whipped cream. Be sure to whisk to the bottom of the bowl constantly with the whisk so that eggs do not scramble, and adjust the heat as needed. (You can use an immersion blender for this.)

Taste sauce, and whisk more lemon juice or more sugar if you want. When thick, foamy, and tripled in volume, remove from heat. Place the bowl into the large bowl with ice and continue whisking for a few minutes until sabayon has cooled down.

Divide berries and their juices into dessert cups. Spoon cooled sabayon over the berries and serve, or, divide berries into dessert glasses and chill. When ready to serve, spoon sabayon over the top.