Try adding hard-boiled eggs to your tuna salad for the ultimate protein boost! To make a delicious tuna salad sandwich with eggs, drain a can of tuna and place it in a mixing bowl. Add chopped hard-boiled eggs, pickles, red onion, and mayonnaise to the bowl. Mix everything until it's well combined. The eggs make the salad creamier and add extra protein, while the celery and red onion give it a great crunch.