Set up a double boiler, with a pot that can snugly fit the bowl of a stand mixer.

Combine the egg whites and sugar in the stand mixer bowl. Stir to mix.

Set the bowl over the pot with boiling water. Using a rubber spatula, stir constantly until the sugar is completely dissolved into the egg whites, and they reach 160ºF (use an instant read thermometer to test).

Affix the bowl to the stand mixer set with the whisk attachment. Add the lemon juice. Starting on low, and gradually increasing the speed to high, beat the whites until it forms a glossy meringue with stiff peaks that cling to the spatula without slipping off, 6 to 8 minutes.

At this point you can use the meringue to top pie, baked Alaska, and toast with a torch, or pipe onto a parchment lined baking sheet to bake in a 200ºF oven. The exact time for them to dry out depends on the size. Medium, button-like meringues will take 75 to 90 minutes. Individual, pavlova-sized meringues will take 1 ½ to 2 hours. Once dried out, turn the oven off, leave the door ajar, and let meringues rest inside until completely cooled.