Fill a deep, wide pan with three inches of water. Add salt and white wine vinegar. Bring to a boil, then reduce to medium.
Place salmon fillets in the water and maintain a gentle simmer for six minutes or until the internal temperature reaches 140°F to 145°F.
Prepare the cucumber sauce by combining cucumber, salt, sugar, white wine vinegar, dill leaves, and sour cream in a bowl.
Serve the poached salmon warm or cold with the cucumber sauce spooned on top. Alternatively, cool the poached fish and use it in other dishes.
