2 Tbs grated onion (grated on the large wholes of a box grater)
2 Tbs Worcestershire Sauce
2 Tbs Dijon mustard
2 Tbs cider vinegar
1 Tbs brown sugar
hot sauce, to taste
2 pounds boneless, skinless chicken thighs or breasts, trimmed of excess fat and cut into 1-inch cubes
2 tsp kosher salt
2 Tbs sweet paprika
4 tsp sugar
2 tsp smoked paprika
1/8 tsp cayenne pepper
2 slices bacon, cut into 1/2-inch pieces
For the sauce, bring all the ingredients to a simmer in a small saucepan over medium heat. Cook, stirring occasionally, until the sauce thickens and reaches a ketchup-like consistency and is reduced to about 1 cup, 5 to 7 minutes. Remove from heat. Transfer 1/2 cup of the sauce to a small bowl and set aside to serve with the cooked chicken.
For the kebabs, toss the chicken with the salt in a large bowl. Cover with plastic wrap and refrigerate at least 30 minutes, or up to 1 hour.
For a gas grill, turn all the burners to high, close the lid, and heat 15-20 minutes. Meanwhile, pat the chicken dry with paper towels. Combine the paprikas, sugar, and cayenne in a small bowl.
Process the bacon in a food processor until a smooth paste forms, 30-45 seconds, scraping down the bowl twice during processing. Add the bacon paste and the spice mixture to the chicken and toss to coat using your hands or a rubber spatula. Thread the meat onto skewers, rolling or foldin meat as necessary to maintain 1-inch cubes.
Scrape the cooking grate clean with a grill brush. Leave the primary burner on high and turn off the other burners. Place the kebabs over the hot burner and grill, covered, turning one-quarter of a turn every 2 minutes or so, until well browned and slightly charred, 8 to 10 minutes.
Brush the top surface of the kebabs with 1/4 cup sauce; flip and cook until the sauce is browned in spots, about 1-2 minutes. Flip again and brush with remaining 1/4 cup sauce; continue to cook until browned in spots and cooked through, about 1-2 minutes.
Remove from grill and allow to rest 5 minutes. Serve, passing barbecue sauce separately.