Let's get this party started!
Makes 6 burgers
1 1/2 teaspoons coarse salt
1/2 teaspoon ground garlic
1/2 teaspoon onion powder
2 pounds ground beef
4 ounces mild melty cheese such as Monterrey Jack or Colby
2 medium yellow onions, sliced into 1/2-inch rounds
About 1/2 cup canola oil (a bit more or less as needed)
3 roasted poblano chiles, skin removed
About half a small head of green cabbage
1/4 cup roughly chopped cilantro
6 hamburger buns, such as potato rolls
1. Combine the salt, ground garlic, onion powder and several grinds of black pepper in a small dish. Blend well. Put the meat in a large bowl, sprinkle the seasoning mixture over it and use your hands to work it into the meat evenly.
2. Divide the meat into 6 even balls, then divide each of those balls in half. Cut the cheese into pieces about 1/4-inch thick and 1.5 inches in diameter (depending on the shape of your cheese, you might put a couple of smaller pieces together to make this shape.) Flatten one small ball of meat into a disk, and gently press the cheese into the center of the disk. Flatten another ball of meat into a disk and lay it on top. Carefully pinch the seams together well, all the way around the burger. Then pat the burger into a nice patty shape. Continue with all the burgers, then lay the burgers on a wax paper-lined plate or platter and refrigerate for at least an hour.
3. While the meat chills, remove the stems from the chiles and slit them open vertically down one side. Lay them flat, inside up, and use the back of a knife to scrape away the seeds and large membranes. Cut each chile vertically into 2 pieces and set all the chile halves on a serving dish.
4. Use a knife or mandoline to cut the cabbage into thinly shredded strips, across the horizontal surface of the cabbage to maintain all the nooks and crannies. (Another way to do this is to grate the cabbage on the large holes of a box grater.) In a medium bowl, combine the cabbage and the cilantro and toss to blend well.
5. Preheat the grill to high. Brush the onion rounds with some of the canola oil (reserve the rest of the oil for the buns). Remove the burgers from the fridge. Brush and oil the grill grate and grill the burgers and onions. Watch them and move them around the grill as needed to cook at an even rate. The burgers are done when the outsides are nicely browned and when you put them on the plate, the liquid that accumulates is not red. (If you are used to cooking unstuffed burgers, you may notice that these cook slightly faster, since the thickness of the meat is much less on any given side.) The onions are done when they are soft and caramelized. The whole process should take about 15-25 minutes, depending on the heat of your grill.
6. While the burgers and onions are cooking, brush the cut sides of each bun with the remaining canola oil and place cut side down on the grill. Watch them and remove them when they are lightly toasted.
6. When ready to serve, slice the avocados thinly and spread several slices on the bottom bun of each burger and use a fork or the back of a spoon to gently mash them down a bit (you'll use about 1/3 of an avocado for each burger). Rest the burger on top of the avocados, then lay a half-poblano on top of each burger patty. Top with grilled onions, followed by the cilantro-cabbage. Add the top bun and serve.
To make sure the cheese doesn't melt out, be sure to thoroughly close all the seams when forming the burgers.