In a bowl, mix miso paste, honey, mustard, soy sauce, garlic, ginger, sesame oil, and vinegar. Stir until smooth and well combined. The mixture should be thick but easy to coat.
Cut chicken into bite-sized pieces for even cooking. Add them to the marinade and mix thoroughly so each piece is coated. Cover and let it marinate for at least 30 minutes or overnight for deeper flavor.
Thread the marinated chicken pieces onto skewers, leaving a little space between each piece. This helps them cook evenly and allows heat to circulate better.
Heat your grill or pan over medium-high heat. Place the skewers on the grill and cook for about 5–7 minutes per side. Turn occasionally until the chicken is cooked through and slightly charred.
Once cooked, remove skewers from heat and let them rest for a couple of minutes. This helps retain juices and enhances flavor before serving.