Gyudon
1/4 cup soy sauce
3 tablespoons mirin  
3 tablespoons sake  
2 tablespoons sugar  
1 teaspoon instant dashi powder, such as Ajinomoto\u2019s Hondashi (see Cook\u2019s Note)  
1 medium onion, thinly sliced (about 1 cup)  
1 1/4 pounds very thinly sliced boneless rib-eye (see Cook\u2019s Note)  
6 cups steamed white rice  
4 poached eggs, optional  
2 scallions, thinly sliced  
Shichimi togarashi, for serving, optional  
Pickled red ginger (beni shoga or kizami beni shoga), for serving, optional  
Instructions:
Pour 1 cup water into a 12-inch skillet. Add the soy sauce, mirin, sake, sugar and instant dashi powder, stir to combine and bring to a simmer over medium heat. Add the onions and simmer, stirring once or twice, until they start to soften, about 3 minutes.
Raise the heat to high and bring the liquid to a boil. Add the beef and cook, turning the slices often with tongs, until the meat is barely cooked through, about 1 1/2 minutes. For the tenderest texture, cook the meat as little as possible.  
Divide the rice among 4 bowls and top with equal portions of the beef and sauce. Top with an egg if using. Garnish with the scallions. Add shichimi togarashi and pickled red ginger, if using.  
