Place the eggs into a saucepan. Fill it with just enough water to cover the eggs. Bring the water to a boil, and let the eggs cook for about 5-8 minutes, depending on your preferred yolk texture. (Less time for a jammier yolk, more time for a solid well-cooked yolk).
When done, run the eggs under cold water, then let them sit in cold water to cool.
In the meantime, transfer the mayonnaise, mustard, paprika, vinegar, celery, and chives to a mixing bowl. Mix everything up well until cohesive.
Peel the eggs, cut them in half, and transfer the egg yolks to the mixing bowl. Smash them into the mayo mixture and mix until creamy.
Roughly chop the egg whites into chunks and pop them into the mixing bowl; stir to coat.
Stir in a generous pinch of salt and pepper, and give it a taste. If needed, add more seasoning.
Get your bread and spread egg salad over a slice bread. Top the egg salad with some nice mixed greens and whatever else you'd like, then close the sandwich up and enjoy!