Sprinkle in the flour and stir well to absorb the oil, cooking for around 30 seconds to create a roux.
Gradually pour in the broth while stirring to avoid lumps.
Add the thyme and diced potatoes, mixing everything together. Let it simmer until the potatoes are fork-tender and the soup has thickened, which should take about 25 minutes.
Carefully flake the smoked salmon into the chowder, then stir in the cream and corn. Continue to simmer for another 10-15 minutes until the chowder thickens a bit more.
Serve the chowder hot in bowls, topping with additional smoked salmon, a sprinkle of sliced green onions, and a dash of cracked black pepper if desired.