Arrange the bacon in a large nonstick skillet and heat over medium heat. Slowly crisp up the bacon, cooking for 3 to 4 minutes on each side. Remove the bacon from the skillet and, when cool, chop. Add the EVOO to the remaining drippings and set aside.
While the bacon is crisping, combine the cornmeal and chipotle powder in a shallow bowl. Set up two more shallow bowls, filling one with the flour and the other with the buttermilk. Dip the onion rings in the buttermilk, then dredge the rings in the flour, tossing them lightly in your hands to remove the excess. Dip them once again in the buttermilk, and finally coat them fully with the cornmeal mixture. Place the dredged rings on a cookie sheet and bake until crispy, 15 to 18 minutes.
While the onion rings are baking, place the ground turkey in a large mixing bowl, season with salt and pepper, and mix in the mustard. Divide the meat into 4 equal portions. Shape each portion into a burger, making a well in the center. Fill the well of each with one quarter of the crisp bacon pieces and 2 tablespoons of the cheese.
Carefully form the burger around the cheese and bacon filling, making sure the filling is completely covered. Return the skillet you cooked the bacon in to medium — high heat. Add the burger patties to the hot skillet and cook for 2 minutes on each side, then reduce the heat to medium — low and cook the burgers for 5 to 6 minutes longer, turning occasionally. Do not press down on the burgers as they cook.
Serve each burger on a bed of lettuce topped with sliced tomato, chopped pickles, and a few oven o — rings.
Courtesy of "YUM-0: The Family Cookbook" Clarkson Potter 2008