Prep the tofu: Pat the block dry with paper towels. For best texture, press it for 10–15 minutes under a weighted plate.
Slice into 1/2-inch thick rectangles or squares.
Make the braising sauce: In a bowl, mix soy sauce, gochugaru, gochujang (if using), sugar, rice vinegar, water, garlic, black pepper, and the white parts of the green onion. Stir until the sugar dissolves.
Pan-sear the tofu: Heat neutral oil in a large skillet over medium to medium-high heat. Add tofu in a single layer and cook 3–4 minutes per side until lightly golden at the edges.
Don’t crowd the pan; work in batches if needed.
Add the sauce: Lower heat to medium. Pour the sauce evenly over the tofu. It should simmer, not boil aggressively.
Braise and reduce: Let it cook 5–7 minutes, flipping the tofu once or twice so both sides soak up the sauce.
The liquid should reduce to a glossy coating.
Finish: Turn off heat. Drizzle in sesame oil and scatter the green parts of the green onion and sesame seeds. Gently toss or spoon sauce over the tofu to coat.
Serve: Enjoy with steamed rice, kimchi, and a simple vegetable side.
It’s great warm, room temperature, or cold.