Here is a Recipe for Garlic Teriyaki Sauce. It is actually a very simple recipe but very delicious.
7 cups of soy sauce
7 cups of sake (Japanese rice wine)
7 cups of mirin (also rice wine but a different kind, more used for cooking)
1 cup of sugar
2 tablespoons of minced garlic (you can add more if you want)
Mix all the ingredients in a pan and cook over a medium heat until it boils, stirring constantly so that all the sugar dissolves. That's it!