Cake flour and gentlestirring give sour cream and thyme rolls their soft crumb. Using an icecream scoop tospoon the dough into amuffin tin isahandy way of making manyuniform dinner rolls quickly.
Lightly butter a standard 12-cup muffin tin, and set aside. Stir together yeast, water, and sugar in a small bowl, and let stand until foamy, about 5 minutes. Stir until yeast dissolves.
Whisk together flours and salt in a large bowl. Using a pastry blender, cut in butter pieces until mixture resembles coarse meal. Stir in yeast mixture. Stir in sour cream and thyme until combined.
Spoon a heaping 1/3 cup dough into each cup of muffin tin. Cover with buttered plastic wrap; let rise in a warm place until doubled in size, about 1 hour.
Preheat oven to 400 degrees. Bake rolls 10 minutes. Remove from oven, and lightly brush with 2 tablespoons melted butter. Bake until golden brown, 16 to 18 minutes. Immediately invert and unmold rolls onto a wire rack. Serve warm.