Stir rice vinegar, soy sauce, maple syrup, pepper, paprika and ginger together in a shallow dish. Add tempeh cubes and toss a few times to coat. Allow to marinate while you prep your other ingredients.

Stir all ingredients together in a small bowl. Set aside.

Coat the bottom of a large skillet with 1 tablespoon of oil and place over medium heat. When oil is hot, add tempeh cubes and any excess marinade. Cook until browned, flipping once or twice, about 8 minutes. Remove from skillet and transfer to a plate.

Add remaining oil to skillet. When oil is hot, add sweet potato, cover and allow to cook until sweet potato cubes are softened but still a bit firmer than you'd want to eat them, about 5 minutes. Uncover and flip sweet potatoes once or twice during cooking. Raise heat to high and add Brussels sprouts to skillet. You can add a few more dashes of oil too if your skillet seems dry. Stir-fry until Brussels sprouts are tender-crisp and sweet potato is fork tender. Add tempeh back to skillet along with sauce. Cook just until sauce thickens and coats everything, about 1 minute.

Divide onto plates with rice. Sprinkle with sesame seeds and scallions.