In a food processor, combine poblanos, cilantro, avocados, lime juice, garlic, and 2 tablespoons of olive oil. Blend until smooth, then add salt and pepper. Refrigerate to allow flavors to meld. (Note: This step can be done a day ahead).
In a bowl, toss short ribs with 2 tablespoons of olive oil, Adams rub, and flour.
Place seasoned ribs in a slow cooker with sliced limes. Set heat to low and cook until meat is pull-apart tender, approximately 6 to 8 hours.
Once the meat is tender, shred, and serve on tortillas. Garnish with avocado sauce and any other taco condiments as desired.