Dissolve yeast and sugar in warm water in a large bowl; let stand 5 minutes. Combine milk and margarine in a small saucepan over low heat; heat until margarine melts (do not boil). Remove from heat; stir in mustard. Cool milk mixture slightly. Lightly spoon flour into dry measuring cups; level with a knife. Combine yeast mixture, milk mixture, flour, salt, and pepper in a food processor; process 1 minute. Turn dough out onto a lightly floured surface; knead 3 or 4 times.
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, 45 minutes or until doubled in bulk. Punch dough down; cover and let rest 5 minutes. Sprinkle with cheese; knead lightly.
Divide dough into 12 equal portions. Working with 1 portion at a time (cover remaining dough to keep from drying), shape each portion into a 10-inch-long rope; tie loosely into a simple knot. Place knots on baking sheets coated with cooking spray. Cover and let rise 30 minutes or until doubled in bulk.
Preheat oven to 375°.
Uncover the dough. Combine 1 tablespoon water and egg white; brush over dough. Sprinkle with sesame seeds. Bake at 375° for 15 minutes or until golden brown. Serve warm.