Tokbokki & DIY Rice Cakes: A Piece of Cake!

Ingredients:

110g Rice flour
85ml Boiling water
50g Onion
40g Fish cake (Vietnamese "chả cá")
1 stalk Green onion (spring onion)
200ml Water
15g Brown sugar (can substitute with white or yellow sugar if needed)
40g Gochujang (Korean red pepper paste)
5ml Soy sauce (adjust to taste)
5g Korean red pepper flakes (gochugaru)
Hard-boiled egg
White sesame seeds