FILLING: Combine the hardboiled egg yolks, cauliflower, Greek yogurt, Dijon mustard, apple cider vinegar, salt, and pepper in a small food processor or bullet blender. Blend until smooth and creamy. Transfer the filling to a large zip-top bag. Note: will be easier to pipe this if you allow to cool in the fridge for 1-2 hours. Rinse and dry the sweet peppers, trim the tops, cut in half lengthwise, and remove any ribs and seeds.
SNIP one corner end from the zip-top bag and carefully pipe the filling in to each sweet pepper half. (Note: it can be hard to tell by the eye just how much 1 tbsp of filling piped is- and then you can run out too soon! My advice is to put 1 or 2 peppers you’ll save for you using an actual tbsp to measure the amount so you can get a visual of how much filling, then try to copy this amount with the rest of the peppers using the piping bag).
GARNISH with smoked paprika, if desired. Cover and refrigerate until ready to serve.
Alternate Cooking Method - INSTANT POT FOR HARDBOILED EGGS
PLACE whole eggs on grate over 1” of COLD water in Instant Pot and cook on manual LOW pressure for 12 minutes or HIGH pressure for 8 minutes (consensus is better yolks with low 1 pressure) , then dip into cold water unless using immediately.