In a big enough mixing bowl or sealable container, mix brown sugar, gochugaru, garlic, sesame oil, water and soy sauce until sugar is dissolved. Add chopped green onion and ginger slices.
To ensure that all slices get access to the flavors, separate and dunk each slice into the marinade. Allow it to sit in the refrigerator for at least 30 minutes, which is more than enough time. Although, there is an adequate amount of water in the marinade, to let it sit over night.
Preheat a big enough frying pan at a medium low heat. Thinly sliced round eye will cook fast but a slow, simmer cooking will tenderize it well enough. Flip periodically to prevent burning. Cook for 30 minutes. Cool in a colander to drain access marinade. Set aside and refrigerate when cool.
In a large bowl, combine all prepared (peeled, shredded, cut, veggies, defrosted, etc.)
Remove ginger slices from meat and chop up the meat well. Add meat to veggies and mix all ingredients well. Refrigerate to soften up veggies.