Using your hands, combine the beef, chipotle chiles, onion powder, cumin, garlic, egg, breadcrumbs, and ¼ teaspoon salt until well combined. Do not overmix.
Divide the mixture into 4, then roll each portion into a ball and flatten into a patty. Set aside.
Preheat the grill to 350 F. Once hot, add the burgers directly onto the grates and cook until browned on either side, about 6-10 minutes. In the last 2 minutes of cooking, add provolone slices to patties and cook until melted.
While the burgers are cooking, whisk together the mayonnaise and adobo sauce. Season to taste with salt.
To assemble the burgers, place the cooked patty on the bottom bun and top with 1 tablespoon of chipotle mayo. Add ¼ avocado to the burger, then add the top bun to serve.