You can also serve this cool, refreshing salad as a chunky salsa with baked tortilla chips.
To prepare salad, cook nopalitos in boiling water 10 minutes. Drain. Place nopalitos in a medium bowl; cool. Add onion, corn, cilantro, and beans; toss gently.
To prepare vinaigrette, combine vinegar and remaining ingredients in a jar; cover tightly, and shake vigorously. Pour vinaigrette over salad; toss gently to coat. Cover and chill.