Iowa Loose Meat Sandwiches

It's like Mom's Beefaroni on a bun!  From the Washington Post Food Section on sandwiches, October 5. 

Iowa Loose Meat Sandwiches
Not quite a hamburger and not quite a sloppy Joe, this is said to have first been served in the state’s Maid-Rite restaurants. Serve with mustard and ketchup on the side. 
Servings: 6

Ingredients

• 2 tablespoons extra-virgin olive oil 
• 2 pounds ground beef (20 percent fat) 
• 1 medium onion, cut into small dice 
• 1 cup homemade or store-bought no-salt-added chicken broth 
• 2 tablespoons apple cider vinegar 
• 1 tablespoon low-sodium soy sauce 
• 1 tablespoon Worcestershire sauce 
• 1 chopped chipotle pepper in adobo (optional) 
• 1 tablespoon light brown sugar 
• 1 teaspoon kosher salt 
• 1 teaspoon freshly ground black pepper 
• 6 split hamburger buns, for serving 
• Dill pickle slices, for garnish

Directions
Heat the oil in a large skillet over medium-high heat. Once the oil shimmers, stir in the ground beef and onion; cook for several minutes, until they have browned, stirring vigorously and breaking up any clumps of meat. The end result should look like lots of small crumbles.

Add the broth, vinegar, soy sauce, Worcestershire sauce, the chipotle pepper, if using, the brown sugar, salt and black pepper, stirring to incorporate. Bring to a boil, stirring, then reduce the heat to medium-low and cook until the liquid has evaporated.

Use a slotted spoon to pile a large amount of meat atop each bottom bun half. Garnish with a couple of pickle slices, and serve with the top bun.