So, I found this recipe in one of my mothers old recipe books and LOVE it. I am sure it is the soy sauce! We usually double this because we love it so much.
Oh, and I always use Kokkimon soy sauce because it does not have anything crazy added, and it makes it taste so much better!
1 lb ground beef
1/4 cup dice onion
1/4 cup vegetable oil
1/4 cup soy sauce
Mix all ingredients together. Form into 4 patties. Broil each side at least 5 minutes, or until done.
Serve with whatever side you want.