If you use 6-inch round pan, the cake will be taller. You can also use 7-inch round pan, the cake just won't be as tall.
Line the bottom of the pan with parchment paper. Lightly grease the side of the pan
Soak red beans in water for at least 4 hours or overnight if you plan to cook the beans on the stove. No soaking is required if you cook with a pressure cooker
If cooking the red beans on the stove:
Discard the soaking water. Place the beans and pour 2 cups of water into a pot. Bring to a boil and then lower the heat and cook the beans for 45 minutes to one hour or until the beans are soft. The beans can be mashed when you squeeze with your fingers. Don't throw away the cooking liquid just yet. Proceed to the "prepare the cake batter" step
If cooking the red beans with pressure cooker:
Discard the soaking water. Place the beans and pour 2 cups of water into the inner pot of instant pot. Close the lid and turn the sealing valve to "sealing". Press "pressure cooker" and set the timer to 45 minutes and then do natural release (about 10 minutes to depressurize). If you use larger-size red beans, you need 55 minutes of cooking time and then do natural release. Don't throw away the cooking liquid just yet. Unlock the lid carefully. Proceed to the "prepare the cake batter" step
Prepare the cake batter:
Bring the water in the steamer to a boil if you plan to steam on the stove. Pour 1 cup of water into the inner pot of instant pot if you plan to use a pressure cooker
I measure out the hot liquid from cooking the beans to get 300 grams into a mixing bowl. You can discard the rest. Add brown sugar to the hot liquid. Stir to dissolve the brown sugar
To the mixing bowl, add glutinous rice flour, rice flour, and oil. Use a whisk to combine until the batter is smooth with no lumps. Strain the mixture if necessary
Add all of the cooked beans to the batter
If steaming the cake on the stove:
Pour the batter into the prepared pan. Cover with an aluminum foil. If you use a bamboo steamer, you don't need to cover it with a foil as water condensation gets absorbed by the bamboo and won't drip on the surface of the cake. Place the pan in the steamer and steam over high heat for 30 minutes and then lower to medium-high and steam for another 30-35 minutes. You may need to refill your steamer with some hot water half-way through cooking
To test for doneness, use a skewer or a toothpick and insert into the middle of the cake. No cake batter should stick to it. If there is, steam a bit longer and check again. The cake appears very soft at this point, but will firm up as it cools down
If steaming the cake with pressure cooker:
Place a trivet inside the inner pot. Pour the batter into the prepared pan. Cover with an aluminum foil. Place the pan on top of the trivet
Cover with aluminum foil. Close the lid. Turn the pressure release valve to sealing. Press "pressure cooker" and pressure cook for 45 minutes and then natural pressure
Carefully unlock the lid and remove from the pressure. Check for doneness by using a skewer or a toothpick to insert it into the middle of the cake. No cake batter should stick to it. If there is, cover it back up with a foil and pressure cook for another 5 minutes and check again.
Decorate the cake (optional):
If you choose to decorate the cake with some walnuts, red dates, and white sesame seeds , do so when the cake is still warm. Just gently press the nuts and dates on the surface of the cake. Sprinkle with some white sesame seeds. Proceed to cooling down the cake
Cool down the cake:
Cool down the cake completely at room temperature for at least 12 hours. Lightly oil the knife and cut into the size you want
Storage:
They can be kept at room temperature for 2-3 days. They can also be kept in the fridge for a week. They also freeze very well. I wrap them in a cling wrap and then put in a freezer bag. Thaw at room temperature or in the fridge overnight. Then warm it up briefly in the microwave before serving if you eat them as is or pan fry with some eggs after it has thawed out completely