Bring a large saucepan of water to a boil. Cook pasta according to package directions, drain and rinse well under cold water.
Mix sesame seeds, 1 tablespoon cornstarch and salt in a shallow dish. Cut the block of tofu lengthwise into 8 thin ¿steaks.¿ Pat dry with a paper towel, and press both sides into the sesame-seed mixture.
Heat 2 teaspoons canola oil in a large nonstick skillet over medium-high heat. Add the tofu and cook until golden brown, about 3 minutes per side. Transfer to a plate, cover and keep warm.
Wipe out the pan. Heat the remaining 2 teaspoons canola oil. Add ginger, garlic and chiles and cook, stirring, until fragrant, about 30 seconds. Add snap peas and cook, stirring, until beginning to brown, about 2 minutes more. Add pineapple juice, bring to a boil and cook 2 minutes. Whisk the remaining 1 teaspoon cornstarch and soy sauce in a small bowl until smooth. Add to the pan and cook, stirring, until the sauce is thickened, about 1 minute. Reduce heat to low, add pineapple, sesame oil and the noodles; toss to coat with the sauce and cook until heated through, about 1 minute. Remove the chiles. Serve the noodles with the tofu.