Beat until potato is very smooth.
Heat half and half and 1 tablespoon brown sugar in heavy small saucepan over low heat until thermometer registers 105°F. to 115°F. Remove from heat. Sprinkle yeast over; stir to blend well. Let stand until yeast dissolves and is slightly foamy, about 12 minutes.
Fit mixer with dough hook. Add remaining 5 tablespoons brown sugar, melted butter, salt and cardamom to sweet potato in bowl and beat until smooth and will blended. Add yeast mixture and mix until blended. At medium speed, beat in enough flour, 1 cup at a time, to form soft dough. Beat 3 minutes (dough will be soft).
Turn out dough onto floured surface. Knead until smooth and elastic, adding more flour by tablespoons if too sticky, about 6 minutes. Knead in dried fruits or raisins. Butter large bowl. Form dough into ball and add to bowl, turning to coat. Cover bowl with plastic wrap, then towel. Let dough rise in warm draft-free area until doubled in volume, about 1 1/2 hours.
Butter large baking sheet. Turn out onto floured surface. Divide dough in half. Using rolling pin, roll 1 dough piece to 12-inch-diameter round (if dough retracts during rolling, stop occasionally and gently pull and stretch dough with fingertips, then continue rolling). Repeat with remaining dough piece. Cut each round into 8 equal triangles. Starting at wide end of triangle, roll up toward point of triangle, stretching dough slightly with fingertips as triangle is rolled up.
Brush point lightly with glaze; press to seal. Place rolls on prepared sheet, shaping into crescents and spacing evenly. Cover rolls with towel. Let rise in warm draft-free area until light and puffy, about 45 minutes.
Preheat to 400°F. Brush rolls with glaze. Bake until rolls are golden and sound hollow when tapped on bottom, about 25 minutes.