Steam the tempeh over simmering water for 10 minutes. This mellows any bitterness and opens it up to soak in the glaze. Pat dry.
Whisk together the white miso, maple syrup, tamari, rice vinegar, grated ginger, minced garlic, and water or vegetable broth until the miso is smooth and fully dissolved.
Heat the neutral oil in a large skillet over medium-high heat. Add the tempeh and sear until golden on both sides, about 5-6 minutes total.
Pour the glaze into the skillet. Simmer on low heat covered, turning the tempeh occasionally, until the sauce reduces to a sticky glaze that coats every piece, about 30 minutes. Stir in the toasted sesame oil at the end.
Garnish with sliced scallions and toasted sesame seeds. Serve over rice or alongside steamed greens.
