In a large bowl or liquid measuring cup, mix together the water, soy sauce, mirin, brown sugar, honey and garlic. Pour into a resealable plastic bag, add the chicken, and close. Flip the bag over a few times to coat. Place in the refrigerator to marinate for 1-3 hours. (I recommend placing the bag in a large bowl to be safe).
Prepare The Umami Rice:
Place the dried mushrooms in the warm water for 45 minutes. Transfer to a medium pot along with the rice and soy sauce. Bring to a boil. Stir once, cover, and reduce heat to low. Simmer for 18 minutes, then remove from heat and let stand, covered, for 5 minutes. Fluff with a fork and set aside.
Prepare The Teriyaki Sauce:
In a small or medium saucepan, whisk together the soy sauce, 1/3 cup water, brown sugar, honey, mirin, garlic, ginger, and orange zest. Bring to a boil over medium-high heat, then reduce the heat to low. In a small bowl, whisk together the remaining 2 tablespoons water with the cornstarch. Whisk into the sauce, and continue simmering and periodically whisking until thick, 3-5 minutes. Remove from the heat and measure out 1/2 cup.
Prepare the Chicken:
To cook on a gas grill: Heat a gas grill to medium heat (approximately 350 degrees). Keep one burner off for indirect heat. (For a two-burner grill, leave one side off. For a three-burner grill, leave the middle burner off. Remove the chicken from the marinade, discarding the marinade. Lightly oil the grates with a neutral flavored, high heat oil. Place the drumsticks on the side with indirect heat. Close the lid and grill for approximately 10-15 minutes per side, then brush the drumsticks with the teriyaki sauce and transfer to the direct heat side. With the lid up, continue brushing and turning the drumsticks periodically to cook the sauce onto the drumsticks and char slightly, until the internal temperature has reached at least 165 degrees F.
To cook on a grill pan: Heat a grill pan to medium on the stovetop. Brush lightly with a neutral, high heat oil. Grill the drumsticks until they are cooked through on all sides to an internal temperature of 165 degrees F, brushing with the sauce as it cooks.
Serve the drumsticks with the umami rice and the remaining teriyaki sauce.
Notes
-Shared with permission from Adventures in Cooking, by Eva Kosmas Flores -Instructions slightly adapted