Put tofu on cutting board with drain, top with a plate to squeeze out water. Leave for about 30 minutes. Drain as needed.
Whisk mirin (or sherry), miso, ginger, lemon juice, soy sauce, sugar, chile-garlic sauce and oil in a small bowl until blended.
Drain tofu; pat dry. Cut the block into eight 1/2-inch-thick slabs. Arrange the tofu slices in a single layer in a shallow nonreactive pan; pour 1/3 cup of the marinade over it, turning to coat. Cover and marinate in the refrigerator for 30 minutes to 1 hour.
Preheat oven to 425°F Coat a 9-by-13-inch roasting pan with cooking spray. Arrange cabbage wedges, cut-side down, in 2 rows. Scatter bell peppers around the cabbage. Sprinkle with scallions. Pour the remaining marinade over the vegetables. Cover tightly with foil. Bake the vegetables until tender, 25 to 35 minutes.
When the vegetables are tender, overlap the tofu slices in the center of the pan and baste with any pan juices. Roast, uncovered, until the tofu is heated through, 12 to 15 minutes more.
Remove the vegetables from the pan and put tofu under broiler 2-3 minutes to brown the outside. Flip over and repeat 2-3 minutes.
Sprinkle with sesame seeds and serve.
To toast sesame seeds: Place in a small dry skillet and cook over medium-low heat, stirring constantly, until fragrant and lightly browned, 2 to 4 minutes.