1. Boil potatoes until tender. Drain. Saute onions in water until translucent. Whip potatoes with garlic, parsley, margarine, milk, salt, and pepper. Stir in onions. Set aside.
2. Prepare dough by combining flour, water, and olive oil. Knead until smooth, adding very small amounts (1/8 teaspoon) water, if necessary.
3. Cut off a strawberry-size piece of dough and roll it into a circle. The dough should be rolled quite thin; just thick enough that it doesn't tear too easily. The standard size of pierogies is about a 3" diameter, but I like to make an assortment of sizes.
4. Put 1 tablespoon or so of the potato mixture on the dough circle, fold one side over so it is a semi-circle, and seal shut. You may need some water if the dough has begun to dry out. After all the pierogies have been made, you can either freeze them, refrigerate them for a few days, or go ahead and cook them.
5. To cook, boil pierogies in water for a few minutes. They cook quickly. Heat 1 teaspoon olive oil in a frying pan. Brown pierogies on each side.
You can top pierogies in a variety of ways; tofu sour cream, tomato sauce, salsa, ketchup, etc. Of course, you can also eat them plain.