Healthy Avocado-Egg Salad Sandwich

Sandwich

• 2 large hard-boiled eggs, peeled
• 1/2 medium avocado, peeled, pitted, and cut into 1/2-inch dice
• 1 tablespoon 2% Greek yogurt
• 1/2 teaspoon Dijon mustard
• 1/2 tablespoon finely chopped fresh chives
• Salt and ground black pepper, to taste
• 12 thin cucumber slices
• 4 slices whole-grain bread, toasted