Sweet Potato Croissants

In a large mixing bowl, dissolve the yeast in water; let stand for 5 minutes until foamy. Beat in the sweet potatoes, sugar, shortening, egg, salt and 3 cups of flour. Add enough remaining flour to form a stiff dough. Turn onto a floured surface; knead until smooth and elastic, about 6 to 8 minutes. Place in a greased bowl, turning once to grease the top. Cover loosely with a clean dishtowel and let rise in a warm place until doubled, about 1 hour.

Punch the dough down; divide into thirds. Roll each portion into a 12-inch circle; cut each into 12 wedges. Brush with butter. Roll up from the wide end and place, pointed end down, 2-inches apart on greased baking sheets. Cover and let rise until doubled, about 40 minutes.

Preheat oven to 375°F.

Bake for 13 to 15 minutes or until golden brown. Remove from pans to wire racks.