2 ¼ cups Cake Flour: This low-protein flour is non-negotiable. It provides just enough structure to hold the cake together without creating dense gluten networks. Substitution: If you are in a pinch, you can make your own by measuring 2 ¼ cups of all-purpose flour, removing 4 ½ tablespoons of it, and replacing those with cornstarch. Sift meticulously.1 ½ cups Granulated Sugar: Divided into two parts. One part sweetens the yolk batter, while the other stabilizes the egg white meringue.1 tablespoon Baking Powder: Unlike angel food cake, which relies solely on egg whites, chiffon cake uses chemical leavening for an extra, reliable lift.1 teaspoon Fine Sea Salt: Balances the sweetness and enhances the overall flavor profile.½ cup Vegetable Oil: The defining ingredient! Because oil remains liquid at room temperature, this cake stays incredibly moist even when chilled, unlike butter cakes. Substitution: Canola or grapeseed oil work perfectly. Avoid heavy oils like extra virgin olive oil unless you want a savory undertone.7 Large Egg Yolks: These provide richness, color, and emulsification to the batter. They must be at room temperature.¾ cup Cold Water: You can use water, but for a classic touch, freshly squeezed orange juice or lemon juice is fantastic.1 tablespoon Pure Vanilla Extract: High-quality vanilla is crucial for masking any subtle "eggy" flavors.7 Large Egg Whites: The structural powerhouse of the recipe. They should be at room temperature to achieve maximum volume during whipping.½ teaspoon Cream of Tartar: An acid that stabilizes the egg whites, ensuring they don't deflate when folded into the heavy batter.