I'm so happy to have found this recipe before New York Times Cooking went behind a paywall. I've been making this chicken a lot this summer and I think it's a new favorite. You have to plan ahead a little, but it's easy to put the marinade together the day before, and then even easier to grill the chicken the next day.

Teriyaki Chicken

• 1 cup soy sauce
• 1 cup granulated sugar
• 1 1/2 teaspoons brown sugar
• 3 large cloves garlic, grated
• 2 tbsp of fresh ginger, grated
• 1/4 tsp freshly ground black pepper
• 1 cinnamon stick
• 8 boneless, skinless chicken thighs
• 1 tbsp cornstarch

1. Combine the soy sauce, sugars, garlic, ginger, pepper and cinnamon stick in a small saucepan. Bring to a boil. Reduce the heat to medium-low and allow to thicken for about 3 minutes, stirring occasionally. Remove from heat and allow to cool. Mix in 1/2 cup water.
   
2. Add half of the cooled marinade to a gallon sized ziploc bag along with the chicken thighs. Store the other half of the marinade separately. Refrigerate overnight.
   
3. Preheat your grill. Grill the chicken ~4 minutes per side. Meanwhile, bring the reserved marinade to a boil. Create a slurry with the cornstarch and 1 tbsp of water. Add to the sauce along with 1/4 cup water and keep at a simmer until the chicken is finished. Serve the chicken topped with the sauce
   

Source: NYT Cooking