Beef & Onions Bowl

Start with mostly frozen (difficult to slice if too frozen or completely thawed) beef flank and slice thinly. Marinate for half hour. Slice one small/medium onion and stir fry with a little vegetable oil until onions are softened, then add the beef. I used a teriyaki style marinade from TJ's ,and should've diluted it, so it turned out on the strong side. Here's one from my mom:

• 1-2 tbsp sugar (brown or white), to taste
  
• 1/2 cup soy sauce
• 1/2 cup water
• 1/4 cup (or less) rice wine vinegar
  
• 1 tsp sesame oil
  

Ken thinks this tastes pretty close to Yoshinoya's beef bowl. We like our dishes with spinach and over plenty of rice.