1 For dough, combine flour, 1/2 teaspoon salt and baking powder in bowl and mix well. Add canola oil, sour cream and water to flour mixture, and knead by hand or with dough hook in a standing mixer for 8 to 10 minutes. Reserve dough.2 For filling, mash potatoes, place in an oven to dry, then remove from oven and reserve to cool. 3 Season to taste with salt and pepper and reserve.4 Cook sliced onion with butter very slowly in a pan over low heat until caramelized.5 Season with salt, pepper and chopped thyme and reserve.6 Roll dough into 1/8-inch-thick sheets, then cut out 2-inch circles. 7 Place a heaping tablespoon of filling onto each circle and fold into half-moon shape.8 Seal each pierogi with beaten egg.9 Gently sauté 2 pierogies in olive oil. Top with onions and truffled crème fraîche and serve.10 1. Combine all ingredients and reserve.