This chicken is so simple I almost feel guilty calling it a "recipe", but here we are. A simple marinade of balsamic vinegar, coconut aminos, and dried herbs infuses boneless skinless chicken with flavor, then creates a sticky but not-too-sweet crust once grilled. Be sure to marinate at least 30 minutes. If you're staring into a crazy week and need very quick dinner, prep the marinade in the morning and let it hang out in the fridge all day.
Combine balsamic vinegar, coconut aminos, olive oil, salt, italian seasoning, and garlic powder in a one-cup measuring cup or small bowl. Whisk until emulsified.
Arrange the chicken thighs in a single layer in a baking dish. Pour the marinade over the chicken gently shake to coat all pieces evenly. Cover with plastic wrap and chill at least 30 minutes, ideally 2 hours, and up to 12 hours. Flip chicken once halfway through.
Heat a grill or grill pan over high heat. Transfer the chicken thighs to the grill using tongs and grill for 4-5 minutes. Occasionally baste the raw side of the chicken with the remaining marinade. Flip the chicken, then grill for an additional 4-5 minutes or until an instant read thermometer reads 165°F when inserted into the thickest portion of the thigh.
Transfer to a plate and rest 5 minutes. Slice against the grain and serve.
Do not marinate longer than 12 hours. Marinating chicken in an acid (vinegar) for too long can cause the meat to become more tough.
Marinating for 2 hours is the sweet spot for a flavorful crust and juicy chicken, but as little as 30 minutes will still create a flavorful crust on chicken thighs. Chicken breasts need the full 2 hours for best results, since they tend to dry out on the grill.
Feel free to use the residual marinade to baste the raw side while grilling, but do NOT baste the cooked side with the marinade - because the marinade was exposed to raw chicken, this is an unsafe food practice.