Grilled Poblano Pepper Southwest Burgers

1. Roast the poblano peppers by first rubbing them with a little olive oil. Heat the grill to a medium-high heat, then set the whole poblano peppers over an area of indirect heat area (turn off burners if necessary, or rearrange coals so the peppers aren't directly over the heat source) and close the lid so that they can roast for 10-15 minutes. Turn once or twice to make sure all sides are cooking evenly and the peppers begin to blister.  
2. Move the peppers to the direct heat and grill until the skins are charred, turning to get all sides of the peppers. Transfer to a dish or plate and cover tightly with plastic wrap for 10 minutes until cool enough to handle. Peel the charred skin away from the peppers and slice open to remove the seeds and stem. Cut the poblano peppers into large slices to use for topping your southwest burgers.
3. Alternatively, preheat oven broiler to high, then place the poblano peppers on a foil-lined baking sheet and broil about 8 minutes, turning occasionally, until blackened, then continuing to sweat the peppers as described above.
4. To make the burgers, divide the meat into 6 equal portions, about 6 ounces each or roughly the size of a tennis ball. Gently shape into burgers that are slightly larger than the size of the buns you plan to use, about 3/4-inch thick.  Make a depression in the center of each patty with your thumb and generously season both sides of each patty with salt and freshly ground black pepper.  
5. Heat the grill to medium-high heat, then place the hamburger patties directly over the flames or heat source and grill, covered, for 3-4 minutes on each side for burgers that are medium-rare to medium. If you prefer your burgers to be closer to medium to medium-well done, cook them for 4-5 minutes on each side. During the last few minutes of grilling, top the burgers with the sliced cheese so it can melt and toast the buns.
6. Let the burgers sit for 3 to 4 minutes after removing from the grill so that the juices can redistribute before serving.
7. Assemble the burgers by laying a piece of lettuce on top of the toasted bottom bun, followed by the burger with melted cheese, slices of poblano pepper, tomato slices, onions, and the toasted top bun that has been generously slathered with chipotle aioli.

Chipotle Aioli

1. Combine all of the aioli ingredients except for the olive oil in a food processor or blender and process for 20 seconds.  
2. With the processor running, very slowly drizzle the oil in a thin stream into the egg yolk mixture, taking about 2 minutes to pour all of it in, until completely incorporated and the aioli is emulsified.
3. Refrigerate until ready to use.