¼tspfine sea salt or table salt(make sure not to use kosher salt--the salt needs to be finer)
475 mlegg whites, about 15 large, at room temperature
pinch of cream of tartar
2tspvanilla bean paste or vanilla extract
2cups (480 ml)cold heavy cream
¼cup (31 g)powdered sugar
1tsp vanilla extract
fresh strawberries for garnish, if desired
Preheat the oven to 350° F. Prepare a tube pan by doing absolutely NOTHING to it! That especially means NO GREASE!! We need the tube grease free so the cake will climb up the sides.
Pour granulated sugar into the bowl of a food processor and process until a finer texture is achieved. This only takes a minute or so on high. Dump into another bowl and set aside.
Pour the 2 bags of freeze dried strawberries into the same bowl of a food processor (if you have to do this in 2 batches, that's fine). Process into a fine powder. Divide the strawberry powder equally. Put half into a small bowl and set aside. Place the other half into a medium bowl and measure the flour, cornstarch, and salt into that same bowl.
Dump the contents of the bowl into a sieve set over a large piece of waxed or parchment paper and sift onto the paper. If there are any seeds left in the sieve, throw them away.
Now gather the sides of the paper into a funnel of sorts and place the sieve over the bowl. Pour the flour mixture over the sieve and sift it back into the bowl. Do this 2 more times for a total of 4 times. Set aside.
Squeeze some lemon juice or white vinegar onto a paper towel and rub it in the bowl and on the whisk attachment of a stand mixer. This will remove any grease that would interfere with the egg whites whipping.
Begin whipping the egg whites on medium speed until foamy and white. Add the pinch of cream of tartar. Once the tines of the whisk start to leave trails, begin SLOWLY adding the superfine sugar, about a tablespoon at a time, allowing each addition a good 10 seconds to incorporate before adding the next. When all the sugar has been added, increase the speed to medium high and whip into soft peaks. They will be glossy and when you pull up on the whisk, the peaks won't completely hold their shape to a stiff peak. Don't overmix!
Begin adding the flour mixture into the whites in 3 additions, folding gently each time. Add the vanilla bean paste or vanilla extract in with the final flour addition. Scoop the batter into the tube pan and then take a dull knife (such as a butter knife) and run through the batter to release any large air bubbles.
Bake for 40-45 minutes, or until the entire top is golden brown, the cake springs back when you lightly touch it, and a tester inserted into the middle comes out clean. The cake should be very tall and even an inch or two over the top of the cake pan.
Immediately upon removing from the oven, tip the cake over onto its built-in feet on a wire rack, or the neck of a bottle (if your pan doesn't have feet). Allow to cool completely.
In the bowl of a stand mixer fitted with the whisk attachment, begin whipping the heavy cream until thickened. Add the powdered sugar and vanilla and continue beating until stiff peaks form. Fold in the other half of the strawberry powder. Frost the cake on the top and down all sides. Add fresh strawberries for garnish, if desired.