Make the sauce. Add the peanut butter, white miso, light soy sauce, rice vinegar and mirin to a small bowl. Pour in the warm water and whisk until completely smooth and pourable. Set aside.

Heat the neutral oil in a large skillet over medium-high heat. Add the green onions and cook for about a minute.

Add the ground chicken and spread it into a single layer. Leave it undisturbed for 3 to 4 minutes so it browns properly, then break it up with a spatula and continue cooking for 4 to 5 minutes until no pink remains.

Stir in the gochujang, soy sauce and rice vinegar, then add the garlic and brown sugar. Cook for another 2 to 3 minutes, stirring, until the chicken is glossy and the edges are crisp and caramelized. Remove from the heat.

Meanwhile, bring a large pot of water to a boil and cook the udon noodles according to the package directions. Drain well.

Pour the peanut sauce over the noodles and toss until every strand is coated, loosening with a splash of hot water if it looks too dry.

Divide the noodles between bowls and spoon the chicken alongside. Garnish with cucumber slices, fresh cilantro, extra green onions and sesame seeds, then serve immediately.