Thaw the frozen sundae completely. Then, place the entire vacuum-sealed package into a pot of boiling water and cook for 10 minutes.

While the sundae is boiling, soak the flat sweet potato starch noodles in cold water for at least one hour.

After soaking, drain the noodles, squeeze out excess water, and cut them in half with kitchen scissors.

Prepare the vegetables: slice the cabbage, onion, large green onion, and green chili pepper into bite-sized pieces.

Roughly chop the garlic cloves.

For the perilla leaves, slice half into bite-sized pieces for the stir-fry and thinly slice the other half for garnish.

After 10 minutes of boiling, remove the sundae from the pot. Let it cool slightly, then open the package and slice the sausage into bite-sized pieces.

In a bowl, combine gochujang, gochugaru, soy sauce, rice syrup, and ground black pepper.

Add water to the bowl and mix everything thoroughly to create the seasoning sauce.

Heat olive oil in a large wok over medium-high heat. Add the minced garlic and stir-fry until fragrant and slightly crispy.

Add the sliced cabbage, onion, green onion, and green chili pepper to the wok. Stir-fry for about 2 minutes until they start to soften.

Make a well in the center, pour in the seasoning sauce, then add the soaked noodles and the bite-sized perilla leaves.

Stir-fry everything together until the noodles are fully cooked, soft, and have absorbed the sauce.

Add the sliced sundae to the wok and turn the heat down to medium. Gently mix to combine, being careful not to break the sundae pieces.

Transfer the finished sundae-bokkeum to a serving dish. Using a preheated cast iron pan will keep it sizzling.

Garnish the top with the thinly sliced perilla leaves.

Sprinkle perilla seeds powder over the garnish.

Finally, drizzle with sesame oil and serve immediately while hot.