Place warm rice in a large bowl and sprinkle with 1/2 tsp kosher salt and 1 tsp toasted sesame oil. Fluff the rice, mixing the salt and and oil into the rice evenly. Let cool while you prep the other ingredients.
Marinate the thin slices of steak with 2 tsp soy sauce, 2 tsp sugar, and 2 tsp toasted sesame oil. Set aside.
Quickly blanch the spinach in boiling hot water and cool immediately in ice water. Squeeze the water out of the spinach and mix with a sprinkle of salt and a 1/4 tsp toasted sesame oil. Set aside.
Massage the carrots with a sprinkle of salt and let soften for 2-3 minutes then squeeze any excess water out of the carrots. Sauté the carrots in a non-stick frying pan over medium low heat with a 1/4 tsp toasted sesame oil until slightly soft, 1-2 minutes. Remove from the pan and let cool.
If needed, prep the danmuji by making sure it’s trimmed to fit the length of the seaweed sheets.
Fry the beef in a nonstick frying pan over medium-high heat stirring as needed until cooked through. Remove from the pan and let cool.
Place a sheet of seaweed, shiny side down, on a rolling mat. Evenly spread 1 cup of the prepared rice onto the seaweed, leaving 2 inches uncovered on the top portion of the seaweed. Place 1/4 of the beef, carrots, daikon, and spinach evenly in a neat row in the middle of the rice.
Use both hands and the mat to roll up the rice and seaweed tightly over the fillings until you reach the top of the seaweed where there is no rice. Let the kimbap sit, seam side down, while you repeat with the remaining ingredients.
Lightly brush the rolls with toasted sesame oil then slice into 1/2 inch bite size pieces and enjoy!