Clean the potatoes and cut into thick strips. Soak potatoes in water to remove its starch, then drain and wipe them dry with paper towel. Set aside.
To prepare the peppers, remove the seeds, and slice them into 3" lengthwise and set aside.
Heat a non-stick pan with about 2-3 tablespoons of oil (more if you have larger potatoes), then pan-fry potatoes until golden-brown. Remove and drain them on paper towels to absorb excess oil.
Using the same pan with the remaining oil, cook mashed tofu until golden brown, then add the garlic and red jalapeño. Sauté until garlic is aromatic (skip garlic for an allium-free dish).
Add in the Korean chili peppers and toss for a few seconds, then add in the potatoes.
Season with soy sauce, sugar, and a drizzle of toasted sesame oil.
Toss all ingredients until well-combined. Finish it up with a cornstarch slurry and cook until the sauce is slightly thickened.
Garnish with chopped green onions and serve warm.