Put the water (3 cups) in a medium pot and add the dried kelp and anchovies. Boil it for 10 mins uncovered on medium heat. Take out (& discard) the kelp and continue boiling for a further 10 mins. Take out the anchovy. Sieve through the boiled broth over damp cheese/linen cloth to remove small particles from the kelp and anchovies. (If you don’t mind these particles, you can skip sieving.) This should result in about 400ml of broth. (Check here if you need step by step photo instructions for this process.)
Pour the broth into a wider pot, add the sauce and stir it well. Boil it over medium high heat. (I used a shallow pot and portable gas burner to enjoy Rabokki like a hot pot dish at the table.)
Once the broth starts to boil, reduce the heat to medium low. Add the rest of ingredients and as they cook, stir around occasionally.
(If you're cooking at the table) Add the garnish ingredients and start eating them as they get ready. Otherwise, serve when everything is cooked. Add the garnish ingredients just before serving.