Press the firm tofu to remove excess liquid (about 15 minutes).

In a bowl, combine the miso paste, sriracha, soy sauce or tamari, rice vinegar, sesame oil, sunflower oil, onion powder, and garlic powder; stir until the mixture is smooth and evenly blended.

Tear the pressed tofu by hand into bite-size pieces (you can halve or tear larger pieces first, then break into bites). Place the tofu pieces in a glass bowl.

Pour the marinade over the tofu pieces and gently toss so all pieces are coated; use a silicone brush if needed to ensure thorough coverage. Let the tofu marinate for 15 minutes (preheat the oven to 390°F / 199°C while it marinates).

Arrange the marinated tofu in a single layer on a non-stick baking sheet, baking mat, or parchment-lined tray, leaving a little space between pieces.

Bake for 15 minutes. Remove the tray, gently toss or turn the tofu pieces so other sides are exposed.

Return the tray to the oven and bake for another 15 minutes, until the tofu is browned and crisp to your liking. Remove and serve.