In a large bowl or shallow dish, whisk together the tomato paste, brown sugar, balsamic vinegar, halal Worcestershire sauce, Dijon mustard, smoked paprika, and salt until smooth.
Add the chicken thighs and coat them evenly with the marinade.
Cover and refrigerate for at least 1 hour, or overnight for deeper flavor.
Preheat your grill for direct heat while leaving one side available for indirect cooking.
Remove the chicken from the marinade and place it over direct heat.
Grill for about 6–8 minutes per side until nicely charred.
Move the chicken to indirect heat if necessary and continue cooking until the internal temperature reaches 165°F (74°C).
Let the Grilled BBQ Chicken rest for 5 minutes before serving.
Garnish with fresh parsley and serve warm.