Preheat the oven to 200 degrees. Line a baking sheet with parchment paper.
Fill a medium pot with an inch or so of water and bring to a boil. Use a clean whisk or rubber spatula to stir together the egg whites and sugar in a clean large stainless steel bowl. Once the water reaches a boil, turn off the heat and set the bowl of egg whites over the hot water, so the water isn’t touching the bowl’s bottom, and stir constantly until the sugar has completely dissolved and the mixture is white, frothy and no longer grainy, about 8 minutes.
Remove the bowl. Use a whisk, hand-held electric mixer or stand mixer fitted with a whisk attachment to beat the egg whites on high to very stiff, shiny peaks, 4 to 5 minutes. Gently fold in the lemon zest.
Spoon the mixture into 4 equal mounds on the lined baking sheet. Bake the meringue until it’s dry and crunchy on the outside but still soft and chewy inside, about 6 hours. Let it cool.
Make the whipped cream:
Combine the cream and sugar in a large bowl. Use a knife to scrape the seeds of the vanilla bean into the bowl; discard the pod. Use a whisk or hand-held electric mixer to whip the cream to semi-stiff peaks. Cover and refrigerate until ready to use.
Make the strawberries:
Combine the strawberries, vodka, lemon zest, lemon juice, balsamic vinegar, salt and black pepper in a large bowl. Use a knife to scrape the seeds of the vanilla bean into the bowl, and add 1 tablespoon of the sugar. Stir gently but thoroughly. Give a taste. You might need more sugar if your strawberries aren’t that sweet.
Cover the bowl with plastic wrap and pop it in the fridge. Let the mixture chill for at least 30 minutes (with the occasional stir) and up to an hour. The longer it sits, the more flavor the vodka will extract from the berries.
Make the Eton Mess:
Crumble the meringues into a large mixing bowl; you should have a combination of small crumbles, medium pieces and large chunks. Add the whipped cream and stir gently just until the meringue pieces are coated. Add about three-quarters of the strawberries and their liquid and stir very gently just until the berries are well distributed but you still see streaks of red in the white cream.
Carefully scoop the mixture into a large serving bowl, scatter the remaining strawberries on top, and drizzle on the rest of the liquid. Serve right away.