Soak the onion in cold water 15 minutes. Drain and transfer to a large bowl. While the onion is soaking, combine the vinegar, mustard, oil, salt, and pepper for the dressing in a jar with a tightly fitting lid. Shake well.

Add the chicken, grapes, artichoke hearts, peppers, and black pepper to the red onion. Add the dressing and toss.

Divide Bibb lettuce between 6 serving plates and top with the salad. Sprinkle each salad with the almonds and parsley and serve.