Spray a large skillet with nonstick cooking spray. Place the skillet over medium-high heat and add sesame seeds. Cook 3 to 6 minutes, stirring often until sesame seeds are lightly browned and toasted. Remove from skillet and set aside.
2
In a small bowl, combine soy sauce, vinegar, brown sugar, pepper, and pepper flakes. Set aside.
3
Spray another large skillet with nonstick cooking spray. Place the skillet over medium-high heat and add canola oil. When oil is hot, add garlic, onions, and ginger. Stir-fry 1 to 2 minutes.
4
Add tofu and stir-fry 1 to 2 minutes. Add water chestnuts, sesame seeds, and prepared soy sauce mixture. Stir-fry 2 to 3 minutes to heat through.
5
Prepare 4 servings by rolling small portions of tofu mixture and chopped tomatoes in lettuce leaves. Serve with hot quinoa.