Rinse chicken, pat dry, and set aside.
In a 9-inch microwave-proof baking dish, stir together soy, sugar, sherry, ginger, and garlic.
Add chicken and turn to coat with marinade.
Cover and let stand for 1 hour, turning chicken over after 30 minutes.
Drain and reserve marinade from chicken.
Cover dish with heavy-duty plastic wrap or wax paper and microwave on HIGH (100%) for 3 minutes.
Rotate dish a quarter turn.
Turn chicken over and brush with marinade; re-cover and microwave on HIGH (100%) for 2 more minutes.
Let stand for 3 minutes.
Meat in thickest part should no longer be pink when slashed.
Garnish with cilantro.