Start by slicing the beef thinly, about 1/4 inch pieces.
Transfer the sliced beef into a small mixing bowl. Add soy sauce, sesame oil, and 2 minced garlic cloves. Mix well then set aside to marinate at room temperature for 15 minutes.
While the beef is marinating, slice the radish 1/4 inch thick slices.
Heat a pot over medium heat, then add neutral oil. Once the oil is hot, add the marinated beef and saute for 1 to 2 minutes until no longer pink.
Add the radish to the pot then cook for 1 to 2 minutes.
Pour in the water, then add the dried kelp. Cover and simmer for 25 minutes. After 25 minutes, check the radish to see if it's cooked through - the radish should be soft and tender. If it's not, simmer for another 15 minutes.
Add the remaining minced garlic then season with fish sauce, salt, and dashida. Allow the soup to simmer for a few more minutes then garnish with chopped scallions.
To serve, I like to add freshly cracked black pepper on top and enjoy with a bowl of rice.