in a saucepan over medium high heat, add the butter and oil. Once hot, add the chopped leeks and cook for 3 minutes until tender. Add the garlic, carrots, turnip, and rutabaga. Season with a bit of salt and pepper and cook for another three minutes.
Add the white wine and scrape off any bits that may have formed on the bottom of the pan. Add the barley and fish stock. Bring the mixture to a boil and then down to a simmer. Simmer for 15 - 20 minutes.
Meanwhile, in a small saucepan, heat the heavy cream over medium heat with the saffron. Bring it just to a simmer and take it off the heat. Whisk in the flour and set aside.
Mix the cream mixture into the pot and stir to combine. Add all the seafood and let it come to a simmer. Simmer for 5-8 minutes. Season to taste with salt and pepper.
The consistency I was looking for was a creamy soup but thinner then a chowder. Use your judgement when determining how thick you want your stew. If you want it slightly thicker, ladle a 1/2 cup of soup out and whisk in another tablespoon of flour. Bring the stew to a simmer again.