Rinse 1 cup of rice under cold water until the water runs clear. Cook rice according to your preferred method (stovetop, rice cooker, or Instant Pot) with 2 cups of water so it's ready when the beef is done.

In a large 12-inch skillet over medium heat, cook the ground beef, breaking it up with a wooden spoon, until browned and no pink remains, about 5 to 7 minutes. Let it sit undisturbed for a minute or two initially for better browning. Drain excess fat if needed (minimal with 90/10 lean beef).

Add the minced garlic and grated ginger to the pan and sauté for about 1 minute until fragrant, stirring constantly to prevent burning.

Stir in the brown sugar, soy sauce, sesame oil, and red pepper flakes. Mix well, scraping up any browned bits from the bottom of the pan with your wooden spoon.

Let the mixture simmer for 2 to 3 minutes until the sauce thickens slightly and coats the beef with a glossy glaze. The sauce should cling to the meat rather than pool in the pan. Taste and adjust seasoning if needed.

Serve hot over cooked rice (about 1/2 cup rice per serving) and top with sliced green onions, sesame seeds, and any optional toppings like shredded carrots, cucumber slices, or a fried egg.