Toss the pressed tofu cubes with salt and cornstarch in a bowl until every side is thoroughly and evenly coated with starch.

Whisk together the gochujang, vegetable broth, maple syrup, sesame oil, ketchup, soy sauce, rice vinegar, minced garlic, and cornstarch until the mixture is smooth.

Heat a large nonstick or cast-iron skillet over medium-high heat with enough neutral oil to coat the bottom. When the oil shimmers, add the tofu cubes in a single layer.

Pan-fry the tofu for about 10 minutes, flipping every 2 minutes, until the cubes are deeply golden brown and crisp on all sides. Transfer them to a paper towel-lined plate to drain.

Sauté the onion and garlic in the same pan over medium-high heat until they become aromatic and slightly softened, about 2 minutes.

Add the bell pepper and cook until tender-crisp, about 2 minutes.

Pour the sauce mixture into the pan and lower the heat to medium. Simmer while stirring constantly until the sauce bubbles and begins to look glossy.

Fold the crispy tofu back into the pan, tossing gently for 3 to 4 minutes so the sauce thickens and clings to the starch coating.

Serve immediately over rice or noodles while the tofu is hot and the sauce is sticky, garnishing with sesame seeds and scallions if you like.