For the blackening seasoning:
1. In a small bowl, stir together dried thyme, paprika, granulated sugar, onion powder, garlic powder, salt, ground black pepper, cayenne powder, and dried oregano.
For the cheese sauce:
1. Fill a medium saucepan with 3 cups water. Add cauliflower and carrots. Bring to a boil and cook for 8 minutes, until vegetables are tender. Remove from heat and drain well.
2. To a food processor or blender, add cauliflower florets, sliced carrots, olive oil, water, lemon juice, nutritional yeast, onion powder, and salt. Puree until consistency is smooth.
For the cheesesteak:
1. In a medium size bowl, toss sliced seitan with blackening seasoning to coat.
2. In a large skillet, heat 1 tablespoon olive oil over medium heat. Add sliced green peppers, mushrooms, and onions. Season with salt and pepper. Cook, stirring frequently for 5 minutes, until peppers and onions are softened. Remove peppers and onions from the pan.
3. To the same skillet used for cooking the peppers and onions, add remaining 1 tablespoon olive oil. Add seasoned seitan and cook 5 minutes, until heated through.
4. Add peppers and onions back into the pan with the seitan and lightly toss together.
1. Divide seitan and pepper mixture between hoagie-style sandwich rolls. Top with cheese sauce and serve warm.