Cut the block of tofu in half width-wise. Arrange tofu on a wire cooling rack on top of a kitchen towel that has been folded into 3 layers thickeness and place over a medium sheet pan. Place another kitchen towel that has been folded into 3 layers of thickness over tofu and place another medium sheet pan over top. Place something heavy like a textbook or several cans on top of sheet pan and allow tofu to be pressed 30-60 minutes.
Cut pressed tofu into 1-in cubes and place in a large bowl. Add 1/3 cup cornstarch and toss until evenly coated.
Heat about 2 tablespoons oil in a large nonstick skillet over medium-high heat. Once oil is hot, add tofu in a single layer (work in batches if necesssary, adding more oil as needed) and cook on all sides, turning occasionally until crispy and browned. Transfer tofu to a wire cooling rack and set aside for a moment.
Drain oil and wipe skillet clean. Add soy sauce, rice vinegar, brown sugar, gochujang, garlic, ginger, and sesame oil. Bring to a low simmer over medium heat.
In a small bowl, whisk remaining 1 tablespoon cornstarch with 3 tablespoons water until smooth. Whisk into sauce and cook until sauce is bubbly and thickened. Toss tofu into sauce until evenly coated.
Assemble the bowls by starting with rice and topping with korean bbq tofu and mango slaw. Top bowls with green onions and sesame seeds. Serve bowls immediately and enjoy!