Preheat the oven to 325°F (170°C, or gas mark 3) and place a rack in the center.
For the Yolk Batter:
Heat the oil in a saucepan over medium heat, until it reaches about 176°F (80°C). Remove from heat. Add the cake flour and whisk until combined. Transfer the mixture to a large bowl, cover, and cool for a few minutes.
Mix in the coconut milk. Add the egg yolks, baking powder, hojicha powder, and sugar and whisk until combined and smooth. Set aside.
For the Firm Peaks Meringue:
Using a stand mixer or hand mixer, beat room-temperature egg whites and a stabilizing acid (like vinegar, cream of tartar, or lemon juice) on medium-high speed until foamy and opaque, a few minutes.
Lower the speed to add the sugar in increments. Turn the speed back to medium-high.
For stiff peaks, whip the meringue until glossy and tripled in volume. The peak will be tall, sharp, and pointing upward. (Overbeaten egg whites will be clumpy, like curds)
For the Final Batter.
Add one-fourth of the meringue to the yolk batter. Gently whisk until incorporated. Add another fourth of the meringue to the yolk batter and whisk until incorporated. Then pour all the batter into the bowl with the remaining meringue.
Use a flexible spatula to gently fold the meringue into the batter, until homogenous, thick, and creamy. There should be no white streaks remaining in the batter. If stubborn lumps of meringue remain, use a whisk to gently mix them into the final batter.
Pour the batter into an ungreased 9-inch (23 cm) tube pan.
Tap the pan against the counter a few times. Smooth out the top of the batter with the whisk.
Spray a large sheet of aluminum foil with cooking spray and place it over the top of the pan. Bake the cake for 25 minutes. Carefully remove the aluminum foil. Reduce the temperature to 310°F. Bake for an additional 20 to 25 minutes, until thoroughly cooked and golden brown. Insert a bamboo stick into the cake. If it comes out clean, the cake is ready.
Remove the cake from the oven. From a height of about 3 inches (7.5 cm) above the counter, drop the cake pan down to shock the cake. Repeat two more times.
Invert the pan and place the tube on a lidded jar or an inverted cup. Cool completely before removing the cake from the pan. Be patient as this can take a few hours. Run a knife gently along the edges where the cake adheres to the tube pan to remove the cake.
Enjoy a slice with hot tea. While this cake is lovely on its own, feel free to serve it with a sprinkle of powdered sugar and segmented oranges.
You will need an 8 or 9-inch angel food cake pan (tube pan).