Preheat oven to 160°C/320°F.
Combine cream cheese, salt and sugar in stainless steel bowl. Sit the bowl in hot simmering water, cook until melted. Add in corn oil and milk, mix until combined. Set aside to cool.
Combine cake flour and baking powder, sift through and mix well.
Add egg yolks to cooled cheese mixture, mix until combined. Add in grated lemon zest and lemon juice, mix well. Sift in flour, mix until just combined (do not overmix).
Whisk egg whites on low speed until large bubbles are formed. Add in cream of tartar, whisk until tiny bubbles. Add in sugar gradually, whisk until stiff peak (the peaks will point straight up and hold). (Reminder: Egg whites and equipment used to beat egg whites must be grease-free and water-free (including egg yolk). It is advisable to clean the egg shells and equipment with dishwasher detergent, then dry with a clean cloth. Use a clean small bowl to separate the egg yolk and egg white, if the egg yolk cracks, don’t use that egg white.)
Add meringue into batter in 4 batches, mix gently using balloon whisk.
Fold gently until well mixed with spatula.
Tap mixing bowl on countertop for a few times to burst large bubbles, then pour batter into 22-cm loose base tube pan (do not grease), tap tube pan gently again on countertop for a few times.
Put into preheated oven, bake at 160°C/320°F for 50-55 minutes, until the top is golden brown. (Reminder: The heat for different oven is different, the suggested time is only for reference, adjust the baking time base on your oven if necessary.)
Turn the pan upside down onto a wire rack (at least 6″ from countertop), set aside until fully cooled.
Unmould the cake when it has fully cooled down.