1: Finely chop the onion, celery, and green onions.
2: Place all chopped ingredients in your stand mixer.
3: Add mayonnaise, stone mustard, salt, pepper, juice from the lemon, relish, and tuna.
4: Mix all ingredients until well combined.
5: Fold in rice crispy cereal gently.
6: Serve on your choice of bread or croissant.
