Delicate green bean cake with smooth, crumbly texture is a refined Chinese pastry. A family recipe with fresh, naturally sweet mung bean flavor.
Soak the dried mung beans in water for at least 4 hours or overnight for the softest texture.
Drain and rinse the beans, then steam them over medium-high heat for 30–35 minutes until very soft and easily mashed.
While still warm, mash the beans thoroughly into a smooth paste using a potato masher or food processor for an ultra-fine texture.
In a nonstick pan over low heat, combine the mung bean paste, powdered sugar, and salt, stirring constantly for 6–8 minutes to dissolve the sugar and reduce moisture.
Add the unsalted butter and vanilla extract, stirring gently until fully incorporated, then continue to cook on low for 3–5 minutes until the paste holds shape and leaves the sides of the pan.
Remove from heat, allow to cool briefly, then press the mixture into small molds or shape by hand. Let cool completely to room temperature before serving for the best crumbly yet smooth finish.