In a large heavy pan over medium heat, heat 2 TBSP (give or take) olive oil. Add the fennel, onion, and leeks, season with salt and pepper to taste, and cook gently for 15 minutes, stirring occasionally. When the leeks are very well-cooked, add the garlic, and cook for one minute more. 

Add the wine. Stir. Add the stock and potato soup; stir. Taste and season with more salt and pepper, to taste. Bring to a light boil and then lower the heat and simmer your stew for 30 minutes, uncovered. 

Add the seafood in the following order: first the fish fillet pieces, then the shrimp, and finally the mussels. Don’t stir! Allow the contents of the pot to come to a simmer, lower the heat, and cook for 8 to 10 minutes, until all the seafood is cooked through and the mussels are open. Turn off the heat and allow your Cioppino to sit for about 5 minutes, to allow the flavors to blend. Discard any mussels that haven’t opened. 

Serve family-style or ladle into bowls, drizzle with salty scallion oil, and enjoy hot. 

For the Salty Scallion Oil

Combine 1/3 to ½ cup olive oil and the scallions in a blender, along with ½ tsp salt (or to taste) and blend until totally smooth, bright green, and well-mixed. If you want to add more scallions – go for it! Same with the salt. Just season it to your liking and call it good.