In a medium-sized pot, combine the acorn jelly powder, cold water, and salt. Stir well until the powder is fully dissolved.
Set the heat to medium. For the first 3–4 minutes, stir occasionally to allow even heating.
At around the 4-minute mark, switch to continuous stirring for another 4–5 minutes. It will start forming soft peaks—much like whipped cream.
Once the mixture has thickened, add a small amount of cooking oil and continue stirring for one more minute. This step helps to enhance the texture and prevents the jelly from drying out.
Prepare a rectangular glass container for molding. Carefully pour the hot dotorimuk mixture into the container. To spread it evenly, gently shake the container and smooth out the surface using a spatula.
Loosely cover the container with plastic wrap and let it cool for at room temperature least 5 hours or overnight. As it cools, the jelly will firm up to the perfect consistency—firmer than Jell-O, yet tender and bouncy. If your kitchen is warm, you can refrigerate the jelly for faster cooling.
Once fully set, slice the acorn jelly into thin rectangular or bite-sized pieces and enjoy it with a savory soy-based sauce.