Dry roast white sesame seeds over low heat for a few minutes, continuously moving around the pan until they turn a nice golden brown.
Transfer to suribachi or mortar and pestle and grind finely.
In a small bowl, add the ground sesameseeds, soy sauce, tomato sauce, Worcestershire sauce, sugar, and optional hot mustard.
Sesame Seeds - The integral ingredient for the restaurant version of this sauce. Dry toasting the seeds adds another layer of roasted nuttiness. The key is low heat - if the pan is smoking, you've got it too high! Use the smallest burner available. Otherwise, you can skip this step if you prefer and sub with tahini in a pinch.
Soy Sauce - Use a Japanese soy sauce brand such as Kikkoman if you can, otherwise, any soy sauce will still work!
Worcestershire Sauce - This brings in the spices to mimic the store bought version. If you like a strong sauce, double the amount.
Sugar - A kick of sugar helps to round out the saltiness from the soy.
Tomato Sauce - Also known as good ol’ ketchup. Regular tomato sauce works well, as the salt and sugar balances out the other flavours.
Hot Mustard - For those who like it spicy, add a little hot English mustard. Add a little at a time and test, as this flavour can quickly take over.
Tweak the Flavours - Feel free to tweak ingredient amounts to suit your own flavour profile!
Thin the Sauce - For a thinner consistency, add a ½ tbsp of water at a time until you reach the desired consistency and flavour.