1. Heat the butter in a large pan over medium high heat.
2. Add the onion, carrots, and celery.
3. Saute until fragrant and soft.
4. Add the white wine to deglaze the pan and get all those yummy browned bits up in the mix.
5. Add the potatoes, thyme, and 2 cups of the broth. Simmer until the potatoes are fork tender.
6. Whisk the flour into the milk and add to the pan (this helps it thicken up a little bit - more flour = more thickening).
7. Add 1 cup of broth and simmer for 5-10 minutes or until the soup starts thickening just slightly.
8. Add the cream and smoked salmon just before serving. If you let the salmon simmer with the soup for too long, it will get mushy. Taste, adjust, and add the last cup of broth to thin out the consistency of the soup as desired. Season with salt and pepper.