Heat oven to 325 degrees and have ready an ungreased 7-inch tube pan. In a medium bowl, sift together flour, baking soda, salt, and 3/4 cup granulated sugar; set aside.
In a large bowl, whisk together egg yolks, vegetable oil, 1/3 cup water, lemon juice, lemon zest, and vanilla. Add reserved dry ingredients, and beat until smooth.
In the bowl of an electric mixer, beat egg whites on medium speed until foamy. Add cream of tartar; beat on high speed until soft peaks form, about 1 minute. Gradually add remaining tablespoon of granulated sugar; beat on high speed until stiff peaks form, about 2 minutes.
Gradually fold egg-white mixture into the batter; start by folding in 1/3, then fold in the remaining 2/3. Pour batter into pan. Using an offset spatula, smooth the top. Bake until a cake tester inserted in the middle comes out clean and the cake is golden, about 45 minutes.
Remove cake from oven; invert the pan over a glass soda bottle for 2 hours to cool. Turn cake right-side up. Run a table knife all the way down between cake and pan; invert again, and remove cake. Dust cake with confectioners' sugar before serving.