Place seitan in a bowl with the chicken broth, tamari, and 1 tsp. of olive oil and let sit for 15-20 minutes. While marinating seitan, saute the onions, mushrooms, and/or green peppers in olive oil until soft and set aside. Drain seitan (reserving the liquid if you want to use it later as a stock) Add garlic powder, and salt and pepper to seitan and stir to distribute evenly. Heat small amount of olive oil in a pan to a medium-high heat and cook the seitan until outside starts to look brown and the tiniest bit crisp, turning often. At the last minute, add the sauted veggies to the pan again. Remove from heat and lay on a few slices of cheese. Cover pan to let cheese melt and then serve on a roll with ketchup or whatever...and you have the vegetarian version of a Philly chicken cheese steak!