1. Prepare center/”bone”
To make the “bone” of the Osso buco, bring a small pot of salted water to a boil. Peel potato. Using a paring knife, cut potato in half crosswise and smooth out edges. Scoop out centers almost all the way to the bottom, taking care not to puncture through. The finished result should be a cylinder, approximately 2 inches tall and 1-1/2 inches wide, and resemble an Osso buco bone. Place potatoes in boiling water and cook until lightly softened, about 5 minutes. Remove and chill while working on salmon.
2. Prepare Osso Buco
To prepare Osso buco, cut salmon into 4 pieces, each about 3 inches long and 3.5 ounces. Wrap fish, skin side out, around the “potato bone” by laying 2 pieces on their side, top to bottom. Truss with butcher’s twine to secure, making sure twine is tight enough not to slip.
3. Prepare fish
Heat canola oil in a sauté pan over medium-high heat. Season fish with salt and pepper. Sear fish on the “potato bottom” side first, until lightly golden, about 2 to 3 minutes; flip and repeat. Add wine, fish stock, brown sugar, onion, garlic, rosemary, parsley and salt. Cook 4 to 5 minutes or until fish is cooked almost throughout. Remove fish; keep warm. Reduce pan sauce until nicely thickened, about 5 minutes.
4. Make gremolata and serve
In a small bowl, combine the zest, parsley and garlic to make the Gremolata.
To serve, place fish onto plates, gently snip and remove the twine. Drizzle on the sauce and top with Gremolata.