Spray 3- to 4-quart slow cooker with cooking spray. Place pork ribs in slow cooker; sprinkle with salt. In small bowl, mix salsa, chili sauce, cumin and ground red pepper; spoon over ribs.
Cover; cook on Low setting 8 to 9 hours.
Remove ribs from slow cooker; place on serving platter. Into 2-cup measuring cup or bowl, pour 1 cup cooking juices from slow cooker. Stir in tomato paste; spoon over ribs.