While the rice cooks, prep the onion. You will need 1 large onion. Grate 1/2 onion on a box grater so that it becomes juicy, onion pulp. Dice the other 1/2 onion in a medium dice.
Marinate ground beef with grated onion, garlic, soy sauce, sugar, Mirin, and sesame oil.
Heat up wok or cast iron skillet on medium heat. When the pan is warm, add 1-2 Tbsp neutral oil (I use grapeseed oil) and swirl around in the pan. Add onion and saute until soft and translucent, about 2 minutes.
Increase the heat to medium-high heat. Add the marinated ground beef and keep cooking, breaking apart big chunks with a metal spatula or wooden spoon. Initially, a lot of liquid will release from the meat. Keep cooking until most of the liquid has evaporated and the meat has turned dark brown in color with crispy edges, about 8-10 minutes.
Remove from heat and add green onion and sesame seeds.
While the meat cooks down, fry 4 eggs in a cast iron pan or non-stick skillet.
Assemble into bowls: Evenly divide rice among 4 bowls. 1 cup cooked rice is a generous portion so feel free to adjust, according to your preference. Evenly divide ground beef bulgogi over the rice. Top with a fried egg. Enjoy!