Start by pressing the tofu to remove excess water. Wrap it in paper towels and place a heavy object on top for 10 minutes, or use a tofu press. This step is key for getting crispy tofu—it helps the tofu brown instead of steam.
In a small bowl, whisk together garlic, lime zest and juice, sesame oil, soy sauce, brown sugar, water (or broth), and Sambal Oelek. Reserve half of this mixture for later and pour the other half over the tofu cubes to marinate for about 20 minutes.
After marinating, toss tofu cubes lightly in cornstarch. Heat vegetable oil in a non-stick skillet over medium-high heat. Add the tofu pieces in a single layer and cook until golden and crispy on all sides, turning occasionally for even browning.
In a saucepan, pour in the reserved marinade and bring it to a gentle simmer. Mix 1 tablespoon cornstarch with a little water to make a slurry, then stir it into the sauce. Let it cook for 2–3 minutes until thick and glossy.
Lower the heat and pour the thickened sauce over the browned tofu. Stir gently to coat every piece in the sticky glaze. Cook for 1–2 more minutes until the sauce caramelizes slightly and clings to the tofu. Remove from heat and garnish with sliced green onions, cilantro, and sesame seeds.