I just searched on Google and found that I was about the billionth person to come up with this idea, but I swear it just occurred to me on its own. Most of the recipes I found kind of miss the point by just adding the avocado to a standard deviled egg formula when it can easily replace the mayonnaise entirely. Maybe this is the one case where watery Florida avocados are actually superior and Hasses can't sub in so well? It might be interesting to compare and contrast.
I should probably back up here and defend the idea of deviled eggs in general. I've got to admit that I'd be skeptical too if I, at the prompting at a post on TheKitchn and, yes, a desire to try the steamer function on my new rice cooker, had my first homemade deviled egg last week. I was amazed at how different it was from the buffet table atrocities I've encountered before.
The key, I think, is in properly cooking the egg. I used my steamer this time, but I usually coddle them--poaching in the shell, really--by carefully adjusting the temperature so water stays just under a boil. That keeps the whites tender. The second important aspect is pulling the eggs from the heat a few minutes early to get them at the mollet stage with the whites just firm and the yolks moist and maybe a little wet in the center. Eggs done this way are great as is, but work really well in deviled eggs too.
Beyond the properly prepared egg, there's the choice of what to mix into the yolk. There are as many variations here as there are in egg salad recipes. Mostly the same variations, actually, now that I think of it. The basic version is to mix with each yolk: a Tablespoon of mayonnaise, a teaspoon of mustard, a little salt, a little pepper and a touch of something acid. Add a sprinkle of paprika on top to justify calling it deviled. This is obviously rich, but it's also just bursting with flavor if it's well seasoned and not too thinned out with mayo.
As you've probably figured out by now, my questionably innovative innovation here is to leave out the mayo and instead use a Tablespoon of avocado. How well this works depends on the moisture content of your yolks and your avocado so some adjustments may be necessary. Unless it's a particularly old avocado, it probably won't want to completely mix in with the other ingredients, but, for me, the little bits of recalcitrant avocado add some textural interest. But I like my mashed potatoes lumpy, so take that for what it's worth. Beyond that, the texture is indistinguishable from using mayonnaise, just beautifully luscious and creamy. As for the flavor, mild Florida avocado is hard to spot, but I think there's a little something there, and, of course, the greenish tinge is obvious.
I suppose there's a mild health benefit to using, but a Tablespoon of mayonnaise more or less is hardly a big deal. I suppose I'm just enthusiastic about deviled eggs right now and happy to have found another avocado recipe that Florida avocados don't screw up.