Cut the 250 grams boneless skin-on chicken thighs into bite-sized pieces and season on all sides with ¼ teaspoon salt.
250 grams boneless skin-on chicken thighs, ¼ teaspoon salt
Set a large pot of water on the stove over high heat to boil the udon. If you are using pre-cooked frozen udon, you can skip this step.
Heat a frying pan over medium-high heat until hot. Add the 1 tablespoon vegetable oil and then the chicken, skin-side down. Let the chicken fry undisturbed until the skin-side is browned (about 2-3 minutes).
1 tablespoon vegetable oil
While the chicken is browning, grate the 100 grams onion, 60 grams carrot, 10 grams garlic, and 10 grams ginger. Then mix in the ⅛ teaspoon baking soda.
100 grams onion, 60 grams carrot, 10 grams garlic, 10 grams ginger, ⅛ teaspoon baking soda
When the chicken has browned on the skin-side (it's okay if the chicken isn't fully cooked), transfer it to a bowl while leaving as much of the oil behind in the pan as possible. Set the chicken aside.
Add the grated vegetables to the pan you fried the chicken in. It will spatter, so be careful. Sauté this mixture until it has formed a paste and is caramelized (about 3 minutes).
Boil the 240 grams fresh udon for 3 minutes less than what the package directions say. Udon tends to boil over, so be sure to keep an eye on it.
240 grams fresh udon
Add the 2 tablespoons Japanese curry powder to the pan with the caramelized veggie paste and continue sautéing until the mixture is uniform in color and very fragrant.
2 tablespoons Japanese curry powder
Add the 2 ½ cups dashi stock, 2 tablespoons mirin, 1 tablespoon soy sauce, 2 teaspoons chunou sauce, and remaining ¼ teaspoon salt to the pan with the curry paste. Return the chicken to the pan, and add the 100 grams onion. Let this simmer for about 5 minutes, or until your udon is cooked.
2 ½ cups dashi stock, 2 tablespoons mirin, 1 tablespoon soy sauce, 2 teaspoons chunou sauce, ¼ teaspoon salt, 100 grams onion
When the udon is done (3 minutes less than what the package directions say), drain the noodles and wash any extra starch off the noodles with cold water. Add the udon to the curry and simmer until the chicken and udon are cooked through.
To finish the curry udon, turn down the heat to low. Ladle some of the hot soup into a bowl with the ¼ cup sour cream and whisk this together. Keep adding soup and whisking until the sour cream is warm. Pour this into the pan with the curry udon and stir-to incorporate.
¼ cup sour cream, Scallions
Serve the curry udon immediately, garnished with Scallions.