Zest the lemons, juice half of one. Add the zest, juice, ginger, egg yolks, and sugar to a pan off heat. Whisk until really well combined, light and ribbony.
Add the flour, salt, vanilla, and cream, whisk until well combined.
Add to medium heat, whisking constantly until starting to thicken. Remove from heat and continue to whisk until starting to cool and the mixture is thick. Add to a piping bag, chill until cooled. If your mixture breaks (this can happen if the heat is too high), just use an immersion blender to bring it back together. Can be made 3 days in advance.
Add the beer and butter to a saucepan. Cook over medium heat until the butter is melted and just starting to boil.
Remove from heat, add the salt, flour, and sugar.
Add back to medium heat, stirring with a wooden spoon constantly until mixture becomes one large ball and clings to the spoon (this should only take a minute and the pan may be hot enough that you don’t need to reintroduce heat).
Add to a stand mixer with a paddle attachment, allow to cool for ten minutes.
Preheat the oven the 450° F.
Add the eggs one at a time, mixing until the dough starts to come back together (after looking as if it may be breaking) before adding another egg.
Mix for at least 2 minutes after the last egg until the mixture looks creamy, and when you pull the mixer paddle up, it leaves a trail that looks like a bird's beak where the dough slides back down but still clings to the paddle.
The dough should be smooth and sticky. Add to a piping bag with a star tip.
Cover a baking sheet with parchment paper. Pipe long lines of dough onto the parchment, about 1 ½ inches thick and 6 inches long.
Bake for 5 minutes and then reduce heat to 350°F without opening the oven. Bake for an additional 20-25 minutes or until the eclairs are golden brown, allow to cool.
Use a bread knife to slice the top off the eclairs.
Add the sugar and beer to a pot over high heat, stir until sugar has melted, then stop stirring.
Allow to boil until dark amber (swirl the pan if needed, but do not stir).
Grab a pair of tongs and a pastry brush (a clean paintbrush works great as well).
Hold the éclair tops with the tongs, and brush the caramel on the top, work quickly before the caramel cools too much to spread. Be very careful, sugar burns are incredibly painful, use tongs and keep your hands away from the hot sugar.
Pipe the filling into the middle of the eclairs before replacing the top.
Chill until ready to serve