Heat the oil and butter in a medium nonstick skillet over medium high heat. Add the sugar and mix with a wooden spoon until dissolved. Add the onion and cook for 5 minutes, or until the onions are lightly browned and soft. Pour in the red wine, pop the lid on, reduce the heat to low and cook for around 35 minutes, or until beautifully golden and caramelized.
Position a rack about 6 inches from the broiler and heat it to high. Line a baking sheet with parchment paper. Set aside.
Put the bread on the baking sheet and broil until lightly toasted. Set aside the tops. Sprinkle the bottoms with cheese, and broil until the cheese melts, 1 -2 minutes.
Top the bottoms with Black Forest Ham, caramelized onions, Peppadew peppers, avocado, greens and the top of the sandwich.