Japanese Worcestershire-style sauce (or better yet, "Chuuno"-Style sauce)
2 tablespoons (30 ml)
1 tablespoon + 2 teaspoons
1/2 teaspoon (1 cm if from a tube)
(I use a small 2.5 ml measuring spoon for some ingredients. It's called a "chasaji", or "tea spoon". [In Japanese, a western teaspoon is called "small spoon".])
Combine all the ingredients in a bowl and mix. Adjust the amount according to the number of servings.
Just for your info, THIS is the real stuff: Otafuku brand's okonomiyaki sauce.
The real sauce is a little thicker, since I just tried to match the taste (not the texture). Taste-wise, it's a near perfect match.
This is the recipe in which I recommend using the Otafuku sauce: Naniwakko-Style Saucy Yaki-soba/Yaki-udon (Fried Ramen/Fried Rice Noodles), Recipe ID: 1362669. Give it a try!
Story Behind this Recipe
In my yaki-udon (fried rice noodle) recipe (Recipe ID: 1362669), I recommended using Otafuku brand okonomiyaki sauce, but since it may not be available to most of you, I came up with this recipe. (My homemade sauce has fruit purée in it, but this one is made from simple ingredients and tastes just like Otafuku's.)
Carefully measure the ingredients in the amounts listed and mix well!