Heat margarine in medium saucepan over medium heat.
Add onion and saute until nearly translucent; add garlic, stirring constantly and cooking until softened.
Add potato and milk to the pan.
Cover and simmer on low heat, stirring every few minutes or so, until potatoes are cooked, about 15-20 minutes.
Add salmon and parsley and stir. Serve warm. Refrigerate unused portion.