Nearly Nikujaga Soup

Name: Nearly Nikujaga Soup
Ingredients: For almost dashi:; 3 ½ cups store bought or homemade chicken stock; 4 x 4 piece dried kombu, wiped (but not washed) with a clean towel; 1 1/2 inch piece fresh ginger (slightly thicker than your thumb), peeled, cut into six coins, lightly crushed with the back of a knife; For potatoes and pork:; 5 1/2 ounces piece of boneless pork belly; 2 teaspoons canola oil; 1 bunch green onions, white and light green parts only; 2 large russet potatoes (11/2 - 1 3/4 lb); 2 1/2 cups mizuna, washed and thoroughly dried; Shichimi Togarashi for serving; For the braising liquid:; 1/3 cup sake; 2 tablespoons dark brown sugar; 2 tablespoons reduced sodium, gluten free Tamari; 1/4 cup water