Many Japanese brands of katsu or tonkatsu sauce are too sweet for me, so my version is a bit more savory. If you would like it sweeter, you are able to add brown sugar at the end. This sauce works with takoyaki and okonomiyaki as well...enjoy!
Ingredients: 1 medium yellow onion, rough chopped 1 apple, peeled, cored and rough cut 1 tablespoon roughly chopped peeled ginger 1 tablespoon roughly chopped garlic 1 teaspoon black peppercorns Pinch of allspice 2 tablespoons ketchup 2 teaspoons fish sauce 1 cup dashi 1 cup Yugeta or Yamaki Jozo organic soy sauce 1 cup mirin 1 cup sake Murakami Syouten Okinawa brown sugar, optional 1 to 2 tablespoons Morino Yoshino kudzu starch, to thicken
Method: Add the onions to a medium saucepan and cook over medium-high heat, stirring frequently, until a dark brown fond starts to develop on the bottom of the pan, about 3-5 minutes. Turn off the heat and let stand for 5 minutes.
Stir the onions, which will have become wet, to gently take the flavorful fond off the bottom of the pan. Add the apple, ginger and garlic, and cook over medium high heat for about 2 minutes, stirring occasionally. When a light brown fond appears, add the peppercorns, allspice and ketchup, and cook for about 1 minute more. Add the fish sauce to deglaze, then add the dashi, soy sauce, mirin and sake. Bring to a boil, then turn down to simmer and reduce by one-third.
Strain through a fine mesh strainer, and taste for seasoning. Some people prefer a sweeter sauce, and this is the point where you add the brown sugar if desired.
Return the strained sauce to the pot and bring back to a boil. Whisk some kuzu with a little water, then whisk the starch mixture into the sauce. Bring back to a boil to activate the thickener.
Leftover sauce may be stored in an airtight container in the refrigerator for up to 2 months, or indefinitely in the freezer.