Preheat oven to 350°.
Drain and dry tofu, cut into 1" cubes and place in a bowl with olive oil and soy sauce. Mix well and place on a baking sheet and put in the oven 20 to 25 minutes until browned. Remove and keep warm.
Place broccoli, celery, bell pepper and carrots into a skillet with 1 tbsp olive oil on medium heat and saute until softened, 12 to 15 minutes. Remove to a bowl.
In the same skillet, add 1/2 cup broth, soy sauce, sesame oil, vinegar, sriracha, and minced garlic bring to a simmer then stir in the cornstarch dissolved in 1/4 cup broth. Bring to a low boil 2 minutes and add the vegetables back to the skillet and combine well.
In a separate non-stick skillet on medium heat, place chicken and stir to brown, 2 minutes. Add 1 or 2 tbsp. soy sauce and cook until the chicken is done, 2 to 3 more minutes.
Plate the vegetables with desired protein with rice on the side. Add green onion for garnish and additional soy sauce.