To the same pot add the sugar and melt over medium heat. Once the sugar begins to melt, stir slowly to incorporate until all the sugar has melted and turned into dark/amber color (the sugar will smoke, which is a good indicator of the sugar caramelizing). The second the sugar reaches the desired color, immediately remove the pot away from the heat. Slowly add 3/4 cup soy sauce, pineapple juice, rice wine vinegar and 2 tablespoons hoisin sauce. The caramel will harden, but this is okay.