Whisk the mayonnaise, sour cream, adobo sauce, ketchup and lime juice together in a large bowl. Season with some salt and pepper. Fold in the bell peppers and chopped cilantro. Then fold in the crab.
Cut a thin slice off the rounded side of the avocadoes so that they sit flat on a plate. Place the avocado halves, flat-side down, on a platter. Fill the cavities with the crab mixture, dividing equally. Garnish with a cilantro sprig. Serve cold.