In a medium bowl, whisk together the cake flour, ¾ cup sugar, and sea salt.
Place the egg whites in the bowl of a stand mixer fitted with a whisk attachment, or in a large bowl with a hand mixer. Beat on medium speed until the whites are starting to look frothy
Add the cream of tartar (or lemon juice) and continue beating on medium speed until the whites are holding soft peaks.
A tablespoon at a time, add the remaining ¾ cup of sugar to the egg whites while beating at medium speed. (Do not rush this process, as doing it slowly will help create a very stable meringue.)
Once all the sugar is added, add the lemon zest, if using.
Increase the speed to medium/high and whip to stiff peaks. They should look glossy and stand tall. (Don’t over whip or the whites will look dry and crumbly and you’ll have to start over.
Lightly sprinkle the dry ingredients over the egg whites. Using a silicone spatula, begin folding the dry ingredients into the egg whites. This should only take about a minute. Be gentle so that you do not deflate the whites.
Gently spread the batter evenly into an ungreased 9" or 10" tube pan. Bake for 30-35 minutes. Do not open the oven during the first 30 minutes of baking or the cake may fall. The cake is finished when browned and dry to the touch and the top springs back when gently pressed.
Carefully invert the pan, place it on a stable surface, and let it cool upside down for 1 ½ hours. (This will help the cake hold its height.)
Once the cake is completely cooled, turn right-side-up, run a butter knife around the sides, the center, and the bottom of the pan, and remove the cake from the pan. Allow the cake to cool completely before serving.
Serve with strawberries topping and whipped cream.
To store, wrap the completely cooled cake well with plastic wrap and keep under refrigeration for up to 1 week. It is best eaten within the first few days.