Press tofu between paper towels for 10 minutes, then cut into 1-inch cubes.
Toss tofu cubes with cornstarch and salt, then let sit for 5 minutes.
Whisk together sweet chili sauce, soy sauce, rice vinegar, garlic, ginger, sesame oil, and red pepper flakes in a small bowl.
Heat oil in a large non-stick skillet over medium heat. Fry tofu 3–4 minutes per side until golden brown and crispy.
Reduce heat, add the sauce to the skillet, and gently toss to coat the tofu.
Cook for 1–2 minutes until the sauce thickens slightly. Garnish with green onions and sesame seeds. Serve with jasmine rice or quinoa.