Best Beef Teriyaki

I found this recipe on allrecipes.com with the name Korean Beef. I adjusted it, and while I've never had "Korean" beef before, I think this tastes like a better version of the beef teriyaki sticks you get from a Chinese restaurant. Addie and Bill loved it. The sauce was great drizzled over white rice and steamed broccoli too. Enjoy!

Best Beef Teriyaki

• 1 ½ - 2 lbs steak
• 1/2 cup soy sauce
• 2 tbsp white sugar
• 3 tbsp brown sugar
• 2 tablespoons sesame oil
• 3 green onions, sliced
• 5 cloves garlic, crushed
• ½  tsp ground ginger
• 5 tablespoons Mirin

1. In a large bowl, whisk together all the ingredients except the meat. Add the meat, and stir to coat. Cover and refrigerate for at least 1 hour, up to 24 hours.
2. Remove the meat from the marinade and pour the marinade into a small saucepan. Turn the heat on high and bring to a light boil. Boil for 10-15 minutes, or until the sauce begins to thicken.
3. While the sauce is boiling, preheat your broiler or grill. Cook your steaks 3-5 minutes per side, depending on thickness and how you want them cooked. Remember they will cook 1 whole level while they rest (from rare to medium-rare). 
4. Let the meat rest under foil for 5-10 minutes before you cut into it. Serve with sauce on the side for dipping, or drizzled over the steak