Angel food cake is usually one of those fussy cakes I prefer to avoid. Anything that requires special pans and beating and sifting or other steps beyond "dump ingredients into a bowl" is generally more than I want to bother with. For this easy version, I simplified the process and ended up with two heavenly loaves: one to photograph and share, and another to eat all by myself.
Position a rack in the bottom of the oven and preheat to 350 degrees F. Line two 9-by-5-inch loaf pans with aluminum foil, allowing the foil to hang over the long sides by at least 1 inch. Do not grease the pans.
Whisk together the flour and salt in a medium bowl. Set aside.
Whisk the egg whites in a stand mixer fitted with the whisk attachment at medium speed just until they start to look foamy, for 30 seconds. Add the lemon juice and cream of tartar and beat on high speed until soft peaks form, 2 to 3 minutes.
Gradually add the sugar in a slow, steady stream and beat until thickened and shiny, about 2 to 3 minutes.
Add the orange extract and vanilla bean seeds, then decrease to the lowest speed. Add the flour and salt mixture in a steady stream and beat until just combined.
Turn off the mixer as soon as all the flour is added. Fold the mixture with a rubber spatula once or twice to make sure the flour is fully incorporated. Divide the mixture evenly between the two prepared pans.
Bake on the bottom rack of the oven until puffed and slightly golden brown on top, 25 to 30 minutes. Cool the cakes upside down by balancing the edges of each pan on two cans or jars, 15 to 20 minutes. Once completely cooled, remove the cakes from the pan, peel off the foil and serve.