1. Bring a large skillet of water to a simmer over medium heat. Add in the splash of white wine, sliced onion, and the salmon. The salmon should be just covered with water.
2. Simmer at a very low boil for about 6 minutes, or just until the salmon is cooked through. Cooking time will vary according to the thickness of the salmon, but do not over cook.
3. Remove from heat and drain the salmon into a colander. Set aside to cool.
4. Blend together the very soft butter with the olive oil. Blend in the egg yolk, yogurt, lemon juice and salt and pepper. It helps for even blending if these ingredients are at room temperature.
5. Mince the smoked salmon. Chop up the cooled poached salmon. Chop the chives finely.
6. Add the two salmons and the chives into the butter mixture and mix well with a wooden spoon for two minutes or so. Season to taste with more salt and pepper if you wish. Lots of pepper is good.
7. Scrape the mixture into a small terrine dish (any small dish will work as well). Push the mixture into the dish to insure that it is compacted. Cover with plastic wrap and refrigerate 24 hours before serving.
8. To serve, spread on grilled rounds of French bread. Best when at room temperature.

Makes about 2 cups of salmon rillettes.