Rinse the azuki beans carefully until water is clear. Discard any damaged beans that are floating. Drain water and transfer the beans to the pressure cooker (I use an Instant Pot).
Add in 4 cups of water. Cover and lock the lid of your pressure cooker. Make sure the steam release handle points at “sealing” and not venting.
Turn on your pressure cooker and select High Pressure for 15 minutes (10 minutes if you prefer to keep the beans slightly firm). If you’re using an Instant Pot, press “Manual” or “Pressure Cooker”, select “high pressure” and adjust the cooking time.
If you are using a stovetop pressure cooker, cook on high heat until high pressure is reached. Then reduce the heat to low to maintain the pressure for 15 minutes.
When it’s done cooking, the Instant Pot will switch automatically to the “Keep Warm” mode. Let the pressure slowly release by itself for 30 minutes (Natural Release). Before opening the lid, turn the steam release handle to “Venting” and release any leftover pressure. If you’re using the stovetop pressure cooker, remove the pot from the heat and let the pressure release naturally.
Add salt and sugar into the pot.
Press the “Saute” button and select “Low” heat. Let the sugar dissolved completely, stirring occasionally, about 5 minutes.
After cooking for 5 minutes, the soup will be a bit darker in color, too. Keep warm and start preparing the mochi (please scroll down).
Option 2: Stovetop Method
Rinse the azuki beans carefully until water is clear. Discard any damaged beans that are floating and drain.
Put the azuki beans and water in a pot.
Bring the water to a boil over medium-high heat. Once boiling, put an otoshibuta (drop lid) over the azuki beans. Turn down the heat to medium-low and keep it simmering for the next 1 to 1.5 hours. Tip: Otoshibuta will prevent the beans from dancing around too much. You can make it with aluminum foil.
Water will evaporate so you need to keep adding water so the beans are submerged. After 1 hour, pick one bean and mash it with your fingers. If it is mashed easily, it's done. Otherwise, cook another 15 minutes and check. Add sugar and salt and let the sugar dissolved completely, stirring occasionally. Keep warm and start preparing the mochi (please scroll down).
★ Making Zenzai with Red Bean Paste (Makes 1) ★
In a small saucepan, combine the store-bought red bean paste or homemade red bean paste and water and bring it to a boil. Add a pinch of salt and mix well. Adjust the consistency by adding or evaporating water. Keep warm and start preparing the mochi (see next step).
★ To Prepare Mochi and Serve ★
Cut the kirimochi into halves or quarters and place them in the toaster oven (or the oven). If you're using the fresh homemade mochi, add it in the soup to warm up. If it's frozen, then boil it in a pot till soft.
Toast the mochi until puffed up and nicely brown, about 10-12 minutes.
Serve the red bean soup and mochi in a bowl and enjoy!