Place the eggs in a medium saucepan and cover with cold water by at least one inch.
Bring the water to a rolling boil, then immediately remove from heat, cover with a lid, and let stand for 12 minutes.
Prepare an ice bath in a medium bowl; transfer the cooked eggs to the ice bath for 5 minutes to stop the cooking process.
Gently crack and peel the eggs, then dice them into uniform 1/2-inch pieces and place in a mixing bowl.
In a separate small bowl, whisk together the Greek yogurt, Dijon mustard, lemon juice, sea salt, black pepper, and paprika until the dressing is silky.
Add the diced celery and chopped chives to the eggs, then pour the yogurt dressing over the top.
Fold the ingredients together gently using a spatula to keep some texture in the eggs.
Toast the sprouted grain bread until it reaches a golden, crunchy texture.
Arrange the baby arugula on top of the toast and mound the egg salad over the greens.