MIX cheeses, sour cream and onion salt in small bowl with electric mixer on medium speed until well blended.
PLACE beans in food processor or blender container; cover. Process until smooth. Spread evenly onto tortillas; top evenly with cheese mixture. Roll tortillas up tightly. Wrap individually in plastic wrap. Refrigerate at least 30 minutes.
CUT ends from tortillas; discard. Cut each roll-up into 5 slices. Serve with TACO BELL® Thick & Chunky Salsa.