Add mushrooms to a ziplock bag. Add olive oil, orange juice, garlic, chipotle peppers, smoked paprika, lime juice, cilantro, and a large pinch of salt. Seal the bag and marinate 10 minutes or in the fridge up to overnight.
Meanwhile, stir together the mashed avocado, lime juice and zest, and a pinch of salt until smooth and creamy.
Preheat your grill or grill pan to high heat.
Remove mushrooms from the marinade and sear for 5 minutes per side, or until lightly charred and tender. Slice into strips.
Warm your tortillas as desired.
Spread the smashed avocado onto the warmed tortillas, top with the sliced mushrooms, and serve immediately.