Combine 1/2 cup flour, sugar, undissolved yeast and salt in a large mixer bowl. Heat sour cream, water and butter until very warm (120° to 130°F). Gradually add to flour mixture. Beat 2 minutes at medium speed of electric mixer, scraping bowl occasionally. Add egg and 1 cup flour; beat 2 minutes at high speed. Stir in enough remaining flour to make a stiff batter. Cover tightly with plastic wrap; refrigerate 2 hours.
Prepare CREAM CHEESE FILLING and STRAWBERRY FILLING (see recipes below); set aside.
Remove dough from refrigerator; let rest 10 minutes. Roll dough to 12 x 7-inch rectangle. Spread evenly with CREAM CHEESE FILLING and STRAWBERRY FILLING. Beginning at short end, roll up tightly as for jelly roll. Pinch seam and ends to seal. Place seam side down in a greased 8½ x 4½-inch loaf pan. Cover; let rise in a warm draft-free place until doubled in size, about 1 hour.
Preheat oven to 350°F. Bake for 30 to 35 minutes. Remove from pan; cool on wire rack. Prepare VANILLA GLAZE (see recipe below) and drizzle over loaf.
For CREAM CHEESE FILLING: Combine cream cheese, sugar and vanilla in a small bowl. Stir until smooth.
For STRAWBERRY FILLING: Combine strawberries, sugar and corn starch in a small saucepan. Cook over medium heat, stirring constantly, until thick. Remove from heat; let cool.
For VANILLA GLAZE: Combine powdered sugar, milk and vanilla in a small bowl. Stir until smooth.