Preheat the oven to 425F. Place soy curls in a small bowl and cover with warm water. Top with a lid and let sit for 10 minutes to allow soy curls to rehydrate.
Meanwhile, slice the peppers and onions and spread evenly onto a large sheet pan. Mix together the spices until they are combined.
Drain the soy curls and add them to the peppers and onions. Top with olive oil and spice blend, mixing with your hands to thoroughly coat the peppers and soy curls. Bake for 25 minutes, until peppers have started to blacken and soy curls are chewy and brown.
While your peppers bake, prepare the avocado, lime, cilantro, and jalapeño, if using. Heat your corn tortillas in the microwave or individually on a skillet.
When peppers and soy curls are done, remove them from the oven and assemble your fajitas. Place the pepper/soy curls mixture at the bottom of a corn tortilla. Top with avocado, lime, cilantro, and jalapeños. Serve immediately.