Marinade: In a bowl whisk together 3 tbsp soy sauce, oil, water, honey, 2 tsp ginger and 1 clove garlic. Add your beef and mix to combine.
Cover bowl with plastic wrap or pour all into a plastic zip up bag. Toss to coat beef. Refrigerate for a minimum of 30 minutes or longer if you can.
In a large saucepan, combine beef broth with 1/3 cup soy sauce, brown sugar, vinegar, sake, 2 cloves garlic and 1 tbsp ginger. Bring to a boil. Reduce heat and simmer, covered, for 20 to 30 minutes.
Transfer to fondue pot, setting flame to keep at a simmer.
Remove beef from marinade, spear with your fondue fork and fondue each piece for 3-5 minutes or until cooked to desired doneness.
As you fondue your broth will cook down. Have extra broth on hand to top up ensuring your forks with beef are always covered with broth.