Egg Salad Lettuce Wraps

Ingredients

• 1 small red onion, halved and thinly sliced crosswise
• 60 ml apple cider vinegar
• 30 ml water
• 6 hard-cooked eggs, coarsely chopped
• 5 slices bacon, cooked and chopped
• 75 ml mayonnaise
• 60 ml diced celery
• 15 ml grainy dijon mustard
• 1 head Boston Bibb/Butter lettuce, separated into leaves
• 30 ml chopped chives
• pepper to taste