Bring a large pan of water to the boil. Carefully lower in 8 eggs and cook for 6 1/2 minutes for a runny yolk, or 7 1/2 minutes for a slightly more firm yolk. Lift out with a slotted spoon and place into an ice water bath immediately or run under a cold tap until completely cold. Peel and set aside. They seem to peel better from an ice bath and fully cooled.
Heat the olive oil in a frying pan and gently cook the onions and garlic for 8-10 minutes until soft and translucent. Do not brown. Set aside to cool slightly.
Place the onions and garlic in a large bowl with the sausage meat, black pepper, herbs, and mustard. Season with salt and mix everything well with your hands, almost into a paste. Divide into 6 balls.
Place the peeled eggs in a bowl with some of the flour. Make sure they are well coated.
Flatten the sausage meat mixture between 2 sheets of saran wrap, parchment paper, or tin foil until it’s as flat as possible. Place a floured egg in the middle of the sausagemeat. Using your hands, shape the meat evenly around the egg until completely sealed. Place the eggs on a baking tray. Repeat with the remaining eggs. Cover and chill for at least 30 minutes.
Beat the 2 remaining eggs with the milk. Line up 3 bowls – one with the remaining flour,, another with the egg mixture, and a third with the breadcrumbs. Roll each sausage-encased egg in the order of the bowls – first in the flour, then egg mixture, and finally in the breadcrumbs. Chill again for 15 minutes.
Preheat the oven to 350.
Heat oil to 170 degrees and put in 2-3 eggs at a time as soon as the oil gets heated. In my our case we used a small saucepan so the eggs could be fully submerged so we did one egg at a time. Deep fry the eggs covered with sausage for 5 minutes until crisp and golden brown. Do not let it get dark brown. Drain on paper towels and repeat with the remaining eggs.
Place the eggs in a cast iron pan or a baking dish. Place in the preheated oven for 8 minutes.
Enjoy hot with a little sea salt and a dipping sauce. Can be served at room temperature as well.