Peel the outer layers off the onions, then slice them down into ¼-inch slices.*For diced onions chop the onions after slicing them Add the onions to a large bowl and season them with the sea salt. Set the onions aside and allow them to marinate for 60 minutes at room temperature.
Place a large frying pan (or skillet) over medium heat.
When the pan is hot add the butter and olive oil to the pan.
When the butter has melted, add the onions and the macerating liquid to the pan.m the pan.
Let the onions cook, stirring frequently for 20-25 minutes
When the onions have caramelized and nicely browned, pour the vegetable stock into the mixture. This will deglaze the pan.*Chicken stock, wine (white or red), or water can be used instead of the vegetable stock.*Stir the onions around. making sure to get all of the brown, crunchy parts mixed in from the frying pan. The crunchy parts add flavor to the onions. When the liquid has been absorbed remove the pan from the heat. Use a slotted spoon to remove the sauteed onions from the pan.
Let the onions cool for 10 minutes before mixing them with the dip ingredients.
Add the sour cream and cream cheese to a large mixing bowl and mix with a hand mixer or stand mixer until mostly smooth.
Add the cooled caramelized onions to the sour cream mixture.
Fold the onions into the mixture with a rubber spatula *reserve a small amount for garnishing the dip. Add the minced garlic, black pepper, red pepper flakes, Worcestershire sauce, and lemon juice to the mixture. and mix with a hand mixer or stand mixer until completely smooth.
Cover with cling wrap and refrigerator for at least 60 minutes for the flavors to combine.
Garnish with the reserved caramelized onions and fresh herbs.