Place a strainer inside a medium bowl. Drain pineapple chunks into strainer, letting the juice collect in the bowl. Transfer 1 cup of pineapple chunks and ½ cup of pineapple juice to a high power blender. Add chipotle pepper, vinegar, garlic, chili powder, cumin, paprika, oregano, and ½ tsp. salt; blend mixture until completely smooth. Set aside.
Heat 2 Tbsp. oil in a large skillet over medium-high. Once hot, add mushrooms and red onion; cook until softened, about 6 minutes. Add chickpeas and remaining 1 Tbsp. oil; cook 5 to 6 more minutes, stirring only occasionally, allowing the chickpeas to pick up some color and crisp. Season mixture with remaining ½ tsp. salt.
Pour Al Pastor sauce into skillet, and toss with chickpeas and veggies. Cook for 2 to 3 minutes, until the sauce slightly thickens. Remove from heat.
Divide chickpea mixture evenly into 8 warmed tortillas. If desired, finely chop remaining half of red onion to use as topping. Garnish with fresh cilantro, queso fresco (or avocado), and a spritz of fresh lime juice.
