I don’t know what the porridge you want looks like. We are in Henan, and the village likes to make noodle soup. We commonly call it "porridge", and we also make "porridge" with mung beans and other ingredients. From the literal meaning of your question, the method is as follows: put water and washed mung beans and cook them together. While the mung beans are cooking and blooming, put half a bowl of flour into the bowl, then add an appropriate amount of water and stir until it becomes thin. After the mung beans are boiled and blooming, stir the batter while adding it, then cover the pot and wait for about 2 or 3 minutes after the "porridge" inside boils, and a rich aroma will emit. This porridge is OK.

I really like mung bean porridge, especially with some pumpkin in it, my favorite.