Preheat the oven to 350°F (175°C).

Pierce each sweet potato several times with a fork.

Bake the sweet potatoes until they are tender when pierced with a fork, about 30 to 40 minutes.

While the sweet potatoes are baking, prepare the miso-orange sauce.

In a saucepan, combine the orange juice, water, ginger, miso, soy sauce, garlic, and brown sugar.

Bring the sauce to a simmer over medium-low heat.

Cook the sauce, stirring occasionally, until it has reduced and thickened enough to coat the back of a spoon, approximately 15 minutes.

Remove the saucepan from the heat and set the sauce aside.

Once the sweet potatoes are cool enough to handle, slice them in half lengthwise.

Arrange the sweet potato halves face up on a baking sheet.

Spoon the prepared miso-orange sauce evenly over the flesh of each sweet potato half.

Sprinkle sesame seeds over the sauced sweet potatoes.

Turn on the broiler.

Broil the sweet potatoes until the sesame seeds are toasted and golden brown, watching carefully to prevent burning.