Combine the spring onions, brown onion, garlic cloves, ginger, pear, and water in a blender and blend until smooth. Once done, add the mixture to the beef along with ground black pepper, sesame seed oil, brown sugar, fine white sugar/castor sugar, brown rice syrup, brown rice vinegar, and light soy sauce. Mix until the beef is thoroughly coated. Let it marinate for 30 minutes to 1 hour (overnight is great too!).
Wash the sushi rice with 2–3 rinses by placing the uncooked rice in a strainer and running it under water, gently rubbing the rice with your fingers. The washing is to get rid of excess starch so the rice would not be mushy when cooked. Once clean, drain the water well and transfer the rice to a rice cooker. Add water, and salt to the rice and cook it.
In a small mixing jar, add all the ingredients for the Gochujang sauce except the sesame oil. In a pan, heat the sesame oil and then add it to the sauce ingredients. Whisk until everything’s well combined. Set it aside.
Heat oil in a pan on medium heat. Once hot, add the marinated beef (in batches) and fry for 5 minutes. As it cooks, the beef will release liquid, at this point, turn up the heat to medium-high and continue frying for 10–15 more minutes until the sauce thickens and you see little charred spots on the beef. Remove from heat and set it aside.
In a clean pan, heat a little oil over medium heat. Add the carrots and a pinch of salt and flash fry for 3 minutes. Set aside. In the same pan, add a little more oil over medium high heat. Add the mushrooms and sauté for 2 minutes, then add the garlic powder and a pinch of salt. Cook until the liquid releases and evaporates and the mushrooms are slightly charred. Set aside. Finally, add a little more oil over medium heat, add the spinach and a pinch of salt and cook until the liquid releases and evaporates. Set aside.
Scoop some rice into a bowl and arrange the carrots, mushrooms, spinach and bulgogi neatly around it. Drizzle or dollop the gochujang sauce in the middle. Optionally, top with a sunny side up egg, and finish with a generous sprinkle of toasted sesame seeds.