Separate yolks from white and blend them in a food processor for 30 seconds, or whisk by hand for 30 seconds.
Slowly (extremely slow, slower than you think necessary) pour in the warm (not hot) bacon fat until it is gone. This step is crucial to getting the mixture to emulsify, make sure you take your time.
That's it. It's that simple
Some people add lemon juice, dijon mustard or apple cider vinegar, but I've found that I'm happy with just these two ingredients. And it's super simple. If you're worried about the nitrate/nitrite myth, read this post from Chris Kresser.