Drain tofu and wrap in paper towel. Place something heavy on top (I use a cast iron skillet), and let sit for about 15 minutes. Once pressed, cut into 1" cubes.
Meanwhile in a medium bowl, whisk soy sauce with hoisin, sugar and sesame oil. Toss with pressed and cubed tofu, and allow to marinate for 15 minutes, tossing occasionally to coat tofu. Remove tofu from marinate (reserve remaining marinade for the vegetables).
Heat 1 tbsp of canola oil in a wok or a large frying pan over medium-high heat. Add tofu, and cook, stirring frequently until tofu starts to caramelize and turn a deep brown, about 3 minutes. Remove from pan and set aside.
Add remaining canola oil, onion and bell peppers. Cook, stirring constantly, until onion starts to brown and bell peppers have a few char marks on them. About 3 minutes. Vegetables should be a vibrant red and still have some crunch.
Add garlic, ginger and chili flakes, continue cooking, stirring constantly for 30 seconds. Add remaining marinade and tofu back to pan. Toss to coat. Serve over rice with sesame seeds.