To make garlic aioli, combine the mayonnaise, garlic, juice from ½ lemon, salt, and pepper in a large bowl until smooth.
Heat oil in a cast iron skillet until very hot. Add the shishitos and sauté on either side until charred with black spots. Once blistered on both sides, remove from the skillet.
Sprinkle with Maldon and juice from half a lemon. Serve peppers with aioli.