In a large skillet or cast iron pan on med/high heat and drizzle some oil. Add the mushrooms and cook for 2 mins and then add in the onions and peppers. Cook the veggies for 5 mins until they are slightly brown but still not cooked all the way. Take them out in a separate plate and set aside.
In the same skillet, add a little but more oil and add in the chicken. Break down the chicken so you can start achieving the "ground" chicken look. Add in the soy sauce and remaining dry seasonings to the chicken. Cook for 5-7 mins until chicken is fully cooked.
Add the cooked veggie mix to the chicken and give it one good mix. Add the sliced cheese on top and cover skillet with a lid so the cheese melted. Once the cheese has melted turn off the stove and toast the bread.
Cut the hoagie down the middle but not all the way, just enough to stuff them. Place the hoagies under the broiler in the oven for a couple mins until there nice and toast.
Spread the mayo on the bread and fill it up with the chicken cheesesteak mixture! Serve immediately and enjoy!