Peel eggs, and once cooled, mash them together with the yogurt. Remove pits and skins from avocados (here's a quick how-to for getting to the flesh of an avocado if your a newbie to them). Mash avocados, then mix in with the egg/yogurt mixture. Add salt/pepper and other seasoning to taste (I added some cajun seasoning). Stir in chopped celery and spinach. Serve on toasted whole grain bread with slices of fresh tomato.
I am (obviously) no food photographer, but here ya go.