Cook rice, according to package directions.
Prep the 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. In a large bowl, add ground beef, grated onion, garlic, soy sauce, sugar, Mirin, and sesame oil. Mix until well combined with hands or a fork. Set aside.
Cook. Heat a wok or cast iron skillet on medium heat. When the pan is hot, 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.
Garnish. Remove from heat and add green onion and sesame seeds.
Assemble. 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!