Combine water, Sriracha and yeast in a large bowl; let stand 5 minutes until frothy.
Lightly spoon flour into dry measuring cups; level with a knife. Add 2 3/4 cups flour, salt, and egg to yeast mixture; stir until a soft dough forms. Turn dough out onto a floured surface. Knead until smooth and elastic (about 8 minutes); add enough of remaining flour, 1 tablespoon at a time, to prevent dough from sticking to hands (dough will feel sticky).
Place dough in a large bowl coated with cooking spray, turning to coat top. Cover and let rise in a warm place (85°), free from drafts, 1 hour or until doubled in size. (Gently press two fingers into dough. If indentation remains, dough has risen enough.) Punch dough down; cover and let rest 5 minutes.
Roll dough into a 14 x 7-inch rectangle on a lightly floured surface. Roll up the rectangle tightly, starting with a short edge, pressing firmly to eliminate air pockets; pinch seam and ends to seal. Place roll, seam side down, in an 8 1/2 x 4 1/2-inch loaf pan coated with cooking spray. Lightly coat surface of dough with cooking spray; cover and let rise in a warm place 30 minutes or until doubled in size.
Preheat oven to 375 degrees.
Bake for 40 minutes or until lightly browned on bottom and loaf sounds hollow when tapped. Remove from pan, and brush with melted butter. Cool on a wire rack.