2/3 cup soy sauce (i would use low sodium)
1/4 cup mirin (rice wine)
1/4 cup rice vinegar
1/4 cup sugar
1 tablespoon freshly grated ginger
2/3 cup beer
6 skinless, boneless chicken breasts, 4 to 6 ounces each
For the teriyaki marinade, combine the soy sauce, mirin, vinegar, sugar, ginger and beer in a small saucepan. Cook over high heat until the mixture reduces by half. Let cool.
Place the chicken and teriyaki marinade in a plastic bag and seal tight. Place the bag in a cooler with ice packs and let the chicken marinate on the way to the game.
When you get to the parking lot, preheat a portable grill.
Grill the chicken on each side until it is cooked through, about 4 to 6 minutes per side.