- Cut seitan into ½-inch pieces. (you should have 1½ cups.)
- In large, nonstick skillet, heat 2 teaspoons oil over medium heat.
- Add seitan and cook, stirring occasionally, until browned, about 6 minutes.
- Remove from pan and set aside.
- Wipe out skillet.
- Heat remaining teaspoon oil over medium heat.
- Add onions and cook, stirring often, until beginning to brown, 5 to 6 minutes.
- Add garlic, red peppers and oregano and cook, stirring often, 5 minutes.
- Stir in broth and seitan and simmer until red pepper is tender, 3 minutes.
- Add scallions and salt and black pepper to taste.
- Stir 1 to 2 minutes more.
- In food processor, make sauce by combining avocado, yogurt, jalapeno, lime juice and ¾ teaspoon salt.
- Process until smooth and creamy.
- Add cilantro and pulse to combine.
- Taste for salt and add more if necessary.
- Warm tortillas briefly in heated skillet.
- Serve tortillas mounded with seitan mixture and generous dollop of avocado-yogurt sauce.