Beef Sukiyaki

Ingredients:
2 tablespoons soy sauce
1/3 cup basic brown stock
1/2 cup sweet rice vinegar
1 pound beef sirloin, sliced paper thin
8 small scallions, cut diagonally into 2-inch pieces
1/2 cup bean sprouts
1 cup loosely packed spinach leaves
1 cup mushroom caps
1/2 cup carrots
1/2 cup slice bamboo shoots
1 cup chicken stock
1/4 cup cooked rice
Procedure:

Combine the soy sauce, brown stock, and vinegar [...]