Preheat grill on medium to medium-high.
Combine in a pot the garlic powder, honey, vinegar and chopped garlic. Put on medium-low heat until reduced to a glaze. About 8-10 minutes.
In a bowl toss chicken with 3 tbsp soy sauce. In another bowl toss broccolini with olive oil, 1 tbsp soy sauce and season with pepper.
Place chicken and broccolini onto the grill. Start glazing the chicken with the honey garlic sauce so it starts to caramelize. Cook the chicken for 12-15 minutes until it reaches 165°F.
Cook the broccolini until tender and nicely charred. About 5-8 minutes.
Remove the chicken and broccolini from the grill and enjoy!