Preheat oven to 400F
In a small saucepan, combine the soy sauce, mirin, Noga (spice from La Boite), Reims (spice from La Boite), brown sugar, orange juice, ginger, garlic, green parts of the green onion, and honey and bring it to a boil over high heat.
Once boiling, decrease the heat to low and simmer uncovered until the liquid is reduced by half. It will take about 30 minutes.
Strain the sauce into a bowl through a fine-mesh strainer and discard the solids. The sauce will be thick and glossy. Let it cool to room temperature before using.
Reserve one-third of the sauce in a small bowl for final coating.
Heat a grill pan over medium-high heat.
Coat grill grates with oil and place chicken thighs onto the grill. Cook until grill marks develop after about 2 minutes.
Brush with ginger sauce and transfer chicken thighs to a baking sheet.
Transfer to the preheated oven and finish cooking.
Tuck the teriyaki chicken thighs into a warm crusty bun and add your favorite toppings.