QUICK "PICKLED" RED ONION: In a medium-sized bowl, combine the thinly sliced red onion, red wine vinegar, salt and sugar. Toss to coat. Leave at room temperature and toss every 5 minutes or so, while preparing the rest of the meal.
SAUCE: Heat the oil in a large skillet. Once oil is warm, add in the thinly sliced sweet onion and garlic. Sauté for 4-6 minutes or until tender, stirring occasionally (nothing should be burning/browning; lower the heat if it is). Add in the tomato paste and all the seasonings: the ground cumin, dried oregano, chicken bouillon powder, paprika, dried coriander, and salt and pepper to taste. (I add 3/4 teaspoon fine sea salt and 1/4 teaspoon cracked pepper.) Toast seasonings for 1 minute, stirring constantly. Again, lower the heat if anything is burning. Add in the crushed tomatoes and cook for 1 minute. Lastly, add in chipotle peppers and sauce (See Note 1). Stir and heat for 30 more seconds. Bring to a simmer, reduce the heat to low, and simmer for 6-8 minutes.
CHICKEN: Transfer the sauce mixture to a large blender and process until completely smooth (See Note 2). Pour the mixture back into the skillet. Add in the 4 cups rotisserie chicken and gently stir to coat the chicken and warm it through. If desired, stir in the fresh lime juice.
QUICK "GUAC": While sauce is simmering, I like to whip this up: Place a large, ripe avocado in a small bowl and mash with a fork. Add in a pinch of salt and pepper and a few squeezes of lime juice. Mash together and set aside.
CHAR TORTILLAS: Spray both sides of the tortillas with olive oil cooking spray and char the tortillas directly over the gas flames for a few seconds. Use tongs to flip until tortillas are lightly charred and soft. Immediately fold the tortilla in half (so it will fold into a taco nicely later) and set aside.
ASSEMBLE: Spread the guac in the center of the charred tortillas. Top with a scoop of the chicken, and some pickled red onions. Add your other favorite taco toppings such as some queso or cotija cheese, some fresh cilantro, and another squeeze of fresh lime juice.