Peel 3 large sweet potatoes and boil them in 2 liters of water with salt, for 20 minutes or until they're tender. Drain and reserve 1/2 cup of the cooking liquid. Mash the sweet potatoes. Reserve the liquid in a pan, add 3 tablespoons of butter, 3 tablespoons of sugar, and 1 tablespoon of salt. Heat until the butter melts. Let it cool. Pour into a large bowl. Sift 2 tablets of active dry yeast over the butter. Mix until the yeast dissolves. Add 3/4 cup of warm milk. Add the mashed sweet potatoes. Add 4 cups of all-purpose flour and mix well. Add more flour (just enough to make the dough smooth). Place on a floured surface and knead until smooth and elastic. Grease a bowl with butter, place the dough, and flip it over to coat evenly. Cover with a cloth and let it rise for 2 hours or until doubled in volume. Punch down the dough. Divide into 4 parts. Open each part to form a circle approximately 22 cm in diameter. Cut each circle into 8 wedges. Roll each one starting from the wider end. Place on greased baking sheets, with the tips of the roll pointing downwards. Cover and let rise for 1 hour. Bake in a moderate oven (170°C) preheated, for 20 minutes or until golden brown. Serve warm. Yields 4 pies.
Peel 3 large sweet potatoes and boil them in 2 liters of water with salt, for 20 minutes or until they're tender. Drain and reserve 1/2 cup of the cooking liquid. Mash the sweet potatoes. Reserve the liquid in a pan, add 3 tablespoons of butter, 3 tablespoons of sugar, and 1 tablespoon of salt. Heat until the butter melts. Let it cool. Pour into a large bowl. Sift 2 tablets of active dry yeast over the butter. Mix until the yeast dissolves. Add 3/4 cup of warm milk. Add the mashed sweet potatoes. Add 4 cups of all-purpose flour and mix well. Add more flour (just enough to make the dough smooth). Place on a floured surface and knead until smooth and elastic. Grease a bowl with butter, place the dough, and flip it over to coat evenly. Cover with a cloth and let it rise for 2 hours or until doubled in volume. Punch down the dough. Divide into 4 parts. Open each part to form a circle approximately 22 cm in diameter. Cut each circle into 8 wedges. Roll each one starting from the wider end. Place on greased baking sheets, with the tips of the roll pointing downwards. Cover and let rise for 1 hour. Bake in a moderate oven (170°C) preheated, for 20 minutes or until golden brown. Serve warm. Yields 4 pies.