Combine the flour and salt in a medium-sized bowl. Cut the butter and cream cheese into several pieces about 1" square. Use a pastry blender to cut the butter and cream cheese into the flour mixture. When the butter and cream cheese are well distributed, mix in the sour cream and water and gather the dough into a ball.
Wrap the dough in plastic wrap and refrigerate for 2 hours or place in the freezer for 30 minutes.
Divide the dough into 4 equal pieces; use one piece at a time and keep the remaining pieces wrapped and refrigerated until ready to use. On a lightly floured pastry board, roll each piece of dough into a 9" circle, a little more than 1/8" thick.
Place the desired filling on the circle of dough; cut the circle into 12 triangles.
Roll each triangle up from the wide end and place on a parchment covered baking sheet about 1" apart. When all the dough has been rolled and filled, bake in a preheated 350 degree oven for about 20 minutes or until the Rugelah are a golden brown.