Spray a skillet with cooking spray and heat over medium heat. Add bell peppers and onion and cook, stirring occasionally, until vegetables are slightly tender, about 5 minutes.
Meanwhile, slice tofu widthwise into 1/4-inch thick slices. Spray a second skillet with a little cooking spray to ensure all surfaces are coated. Lay tofu slices side by side in a flat layer in the skillet; you will have to work in batches. Sprinkle exposed side of each tofu piece with sesame seeds.
Cook over medium heat until tofu is firm, 3 to 5 minutes. Flip each piece of tofu over with a fork. Sprinkle the cooked side of the tofu with sesame seeds and cook until firm and browned, 3 to 5 minutes longer. Remove tofu from the skillet and set aside. Repeat to cook remaining tofu.
Stir teriyaki sauce and honey together in a bowl. Add remaining sesame seeds (there should be at least 1/2 cup left) to the sauce. Pour sauce over the vegetables in the pan and heat on low heat until the sauce thickens slightly, about 5 minutes.
Serve vegetables with sauce over brown rice and top with sesame tofu.