Combine seitan, red pepper, onion and mushrooms in a bowl. Add garlic, sweet and hot paprika, salt, turmeric and black pepper. Mix ell so the spices coat the seitan, then add 2 teaspoons of olive oil and vinegar. Cover and place in fridge for one hour.
Heat 2 tablespoons of olive oil in a large non stick skillet. Add marinated seitan and vegetables (including liquid) and cook over medium high heat for about 20 minutes, stirring occasionally
In the meantime, prepare the tahini sauce: combine tahini paste, salt and lemon juice in a small bowl and mix well. Whisk in water, one tablespoon at a time, until creamy
Fill each hoagie with about 1/3 cup of cooked seitan and top with1 tablespoon of tahini sauce