Slice the shiitake mushrooms into thin 1/8-inch strips and julienne the carrots into 2-inch long matchsticks. In a small bowl, combine the beef mince with 1 tablespoon soy sauce, 1 tablespoon sesame oil, brown sugar, garlic, and ground ginger. Stir well to coat the meat evenly and set aside to marinate while you prepare the vegetables. I find that letting the beef marinate even for just 15-20 minutes while you work on other components really deepens the flavor, so don't skip this step if time allows.
Heat a large skillet or wok over medium-high heat with a light coating of cooking oil. Working with one vegetable at a time, cook the carrots with a pinch of salt for 2-3 minutes until just tender-crisp, then transfer to a plate. Repeat with the mushrooms, cooking them with salt for 2-3 minutes until golden and tender. While the vegetables cook, blanch the spinach in boiling water for 1-2 minutes, then drain well and squeeze out excess moisture. Similarly, blanch the bean sprouts for 2 minutes, drain, and season lightly with salt. Cook each vegetable separately so they maintain their individual flavors and textures rather than becoming a mushy mixture.
In the same skillet over medium-high heat, add the marinated beef from Step 1 and cook for 3-5 minutes, breaking it up with a spoon as it cooks, until browned and cooked through. Transfer to a plate and set aside. The beef should be well-browned to develop deep, savory flavors that anchor the entire dish.
While the beef cooks, whisk together the gochujang, 1.5 tablespoons sesame oil, sugar, water, vinegar, and garlic in a small bowl to create a smooth, well-combined sauce. Set aside. Then fry the 3 eggs in the skillet until the whites are set but the yolks remain runny—this creates a creamy element that brings everything together when you mix the bibimbap. I always prefer runny yolks because they act as a sauce and coat all the ingredients beautifully.
Divide the steamed rice evenly among three bowls, creating a slight well in the center of each. Arrange the cooked beef, carrots, mushrooms, spinach, and bean sprouts from Steps 1-3 in separate sections on top of the rice, keeping them distinct and organized. Place a fried egg from Step 4 on top of each bowl, sprinkle with sesame seeds, and add a sheet of seaweed. Drizzle the gochujang sauce from Step 4 over the top.
Use a spoon to vigorously mix all the components together until the rice is coated with sauce, the egg yolk breaks and creates a creamy texture, and all the vegetables and meat are distributed throughout. Serve immediately while the rice is still warm and everything is at its peak flavor.