Start by thoroughly rinsing your fresh kelp. 
Once rinsed well, place 1/4 cup of the sugar kelp in a pot with 4 cups of water and bring it to a simmer for 5 to 10 minutes. 
Strain out kelp and reserve the broth; this is called dashi and it will be your soup base. 
Return the dashi to the pot and heat over medium, making sure it doesn't boil. 
In a separate bowl, add 4-5 tablespoons of miso paste and mix with a small amount of dashi until completely dissolved. 
Then, add the dissolved miso back into the pot. 
Cut your silken tofu into 1/4 to 1/2 inch cubes and add it to the miso soup with remaining 1/2 cup of kelp and chopped green onion before serving. 

Recipe and photo by Claire Bastarache, National Seaweed Hub