I would like to share this new method of heating up the liquid and mixing it to the dry ingredients while it is hot. Also the sugar is sieved with the flour, salt and baking powder. It does give a finer crumb and improved the texture. i too find that there is no need to add the sugar slowly while whisking the egg whites. It makes no difference, so just add egg whites, cream of tartar and sugar all at once and whisk at a constant slow speed.(speed 4 in kitchenaid mixer)
5 egg yolks
1/3 cup vegetable oil
1/2 cup orange juice(cold from the fridge)
1/2 tsp orange paste
Zest from 1 large orange
3/4 cup cake flour plus 1/3 cup all purpose flour and 2 tbsp(150 gms)
5 tbsps fine granulated sugar(60 gms)(can be reduced 50 gms)
3/4 tsp baking powder
1/2 tsp salt
5 egg whites
1/8 tsp Cream of tarter
7 tbsps fine granulated sugar(85 gms)(maybe increased to 100 gm if using 50 gm for the above)
Preheat oven 325 f.
Sieve 3/4 cup cake flour and 1/3 cup a. p. flour plus 2 tbspa(to make total 150 grams) 3/4 tsp baking powder, 5 tbsp fine granulated sugar and salt, 3 times.
Pour 1/3 cup vegetable oil and 1/2 cup orange juice in a microwave container/pyrex measuring jug
Microwave on high for 1 minute(if orange juice is in room temp. microwave for 30 seconds)(my microwave wattage is 1000 watts so adjust according to your microwave wattage)
Pour hot oil and orange juice mixture into sieved ingredients and using a whisk, mix thoroughly
Add orange paste, zest and 5 egg yolks. Mix until well combined.
Wipe mixing bowl and whisk with vinegar to make sure that it is totally oil free.
Whisk 5 egg whites, 1/8 tsp cream of tartar and sugar at speed 4 kitchenaid mixer until firm and soft peak.
Put 1/3 of whisked egg whites into egg yolk mixture and still using the whisk, mix until mixture is the same texture as the whisked egg white.
Pour this mixture into the egg whites and now using a large rubber spatula, fold the egg whites into the tempered egg yolk mixture, cutting in the middle of bowl at 12 o'clock to 6 o'clock and scooping right to the bottom, lifting mixture over while turning the bowl. Repeat this folding until mixture is well combined with no egg white streaks.
Pour from a higher position into 8 inch ungreased chiffon mould, By pouring from higher position, bubbles will dissipate. Level mixture and bang mould on countertop to remove larger bubbles.
Put to bake in 325f for 40 - 45 mins. (oven temperature defers from oven to oven,)(you can bake at 325f for 10 mins and then reduce to 300f for another 30 - 35 mins)
Remove from oven and invert cake (i like to use a stainless funnel and allow the center hole resting on the funnel) until cold before removing from mould.