Put the wine, water, bay leaves, parsley and one of the sliced lemons in a large skillet and bring to a simmer. Add the salmon skin side down. Add more water if necessary to cover the fillet. Cover the skillet and simmer over low heat until the fish is just cooked through, about 10 minutes per inch thickness. With two large spatulas carefully transfer the fish to a plate, cover it and let it cool. Transfer to the refrigerator to chill completely- about 3 hours.
Once chilled, remove the skin from the salmon. Uncover the fish, place a clean plate or baking sheet on top and flip the two over to the fish is skin side up on the clean plate. Peel the skin from the fillet and scrape away any discolored flesh. Flip the fish again right side up onto a serving plate. Garnish with the scallion greens and the remaining lemon slices.
If using regualr yogurt spoon it into a strainer lined with a paper towel or coffee filter and set over a bowl. Let is drain and thicken for 30 minutes. Coarsely grate the cucumber. Drain it well in another strainer for a minute or two pressing out as much liquid as possible.
In a meduim bowl stir together the drained or Greek yogurt, the grated cucumber oil, lemon juice and zest, garlic and mint. Season with salt and pepper.
Sauce will keep 3 days in airtight container in fridge.