Start by firing up your grill to medium high heat. We’re using the Ninja Woodfire Outdoor Grill to grill our onion and pepper AND bake our meatloaf.
Toss the sliced onions with a few glugs of olive oil and season them with salt and pepper. Grill the onions and pepper until they are soft and get some color, about 10 minutes. Remove from the grill and cool while you prep the rest of the meatloaf.
Combine the beef, breadcrumbs, adobo sauce, cumin, and egg in a large mixing bowl. Roughly chop the peppers and onions and move to a small bowl. Add the chicken broth, tomato paste, and Worcestershire sauce and stir to combine. Add the onion mixture to the meat mixture and use clean hands to combine. Try not to over mix. Move the meatloaf mixture to an 8×8 metal baking pan.
Mix up the ketchup, chipotle pepper, and lime zest and spread this over the top of the meatloaf. Bake the meatloaf for 45 to 55 minutes at 375 degrees F until it is cooked 160 degrees F. Remove the meatloaf and cool for 15 minutes while you toast the bread.
Spread a few teaspoons of mayo on each slice of bread and toast for 30 seconds on each side. Cut the meatloaf into 4 pieces and build the sandwiches with a hunk of meatloaf, two bread slices and some green onions.