In a large heated pan, add a little olive oil and buns, cut sides down, and toast until golden brown. Set aside. In same pan, add more olive oil and saute onions for 7 minutes, while stirring. Add salt, pepper, and sugar and cook together for 3 more minutes. Remove to a bowl. Rinse and wipe pan clean.
Make the special spicy sauce by stirring all the ingredients together into a small bowl. Set aside.
Add beef to a large bowl. Mix slightly with your hands. Divide into 8 separate sections, form into balls, and press lightly to flatten into patties slightly bigger than the size of your buns. Make a slight indentation in the middle of your patties with your fingers. Season with salt and pepper on both sides.
Add a little more olive oil to the pan and place over high heat. Add burgers, and cook for about 3 minutes on the first side. Flip, cook for 2 minutes on the second side, add cheese and cover to melt the cheese, for 1-2 minutes more. Transfer burgers to a paper towel lined plate to drain. To assemble, place arugula on bottom bun, top with bacon strips, add burger, top with a little special spicy sauce, add a pile of caramelized onions, top with the bun, and spear with a toothpick or sandwich pick.