In a bowl, stir together the soy sauce, brown sugar, water, garlic, onion, spring onion, and sesame oil until the sugar has dissolved.
Place the ribs in a large plastic zip lock bag. Pour the marinade over the ribs, squeeze out all the air, and chill the bag for 3 hours to overnight.
Lightly oil a griddle pan on medium-high heat. Remove the ribs from the bag, shake off the excess marinade, and discard the marinade. Grill the ribs until the meat is still pink but not bloody nearest the bone, around 7 minutes per side.