1Boil potatoes in salted water until very tender, about 15-20 minutes. Drain well and pass through a potato ricer or mash thoroughly until no lumps remain. Spread the riced potatoes on a clean surface to cool slightly and allow moisture to evaporate for about 5-10 minutes.

2Form the cooled potatoes into a mound. Create a well in the center and add the flour, egg yolk, and salt. Gently combine the ingredients using your hands, kneading briefly until a soft dough forms. Do not overmix, or the gnocchi will be tough.

3Divide the dough into four portions. On a lightly floured surface, roll each portion into a long rope, about 1.5-2 cm (0.6-0.8 inch) thick. Cut the ropes into 2 cm (0.8 inch) pieces. You can leave them as is, or gently roll each piece over the back of a fork to create ridges.

4Bring a large pot of salted water to a rolling boil. Drop the gnocchi in batches into the boiling water. They are cooked when they float to the surface, typically 2-3 minutes. Remove with a slotted spoon and set aside.

5In a large skillet over medium heat, melt the butter. Continue to cook, swirling occasionally, until the butter browns and nutty aromas emerge, about 5-7 minutes. If using, add diced pancetta/bacon and cook until crispy, then remove with a slotted spoon and set aside, leaving rendered fat in the pan.

6Add the minced garlic and chopped kimchi to the brown butter (or fat from pancetta) in the skillet. Sauté for 2-3 minutes until fragrant. Stir in the gochujang, soy sauce, and rice vinegar, cooking for another minute.

7Add the cooked gnocchi to the skillet with the sauce. Toss gently to coat. If using, stir in baby spinach or kale and cook until wilted, then return the crispy pancetta/bacon to the pan.

8Serve immediately, garnished with sliced green onions and toasted sesame seeds.