Cooking Steps
In a blender, blend cilantro stems, chiles, garlic, orange juice, olive oil, garlic powder, lemon pepper seasoning, onion powder, oregano, and juice of 2 limes until smooth. Transfer to a resealable bag or large bowl. Add steak, turn to coat, and refrigerate about 3 hours.
Cut remaining 2 limes into wedges for serving.
Chop cilantro leaves and set aside for serving.
Prepare a grill for high heat.
Pat steak dry and grill, turning occasionally, until an instant-read thermometer inserted into thickest part registers 130° for medium-rare. Transfer to a cutting board and let rest 15 minutes. Slice across the grain or chop into small pieces.
Using tongs, heat tortillas over a gas burner until browned in spots, about 30 seconds per side.
Slice avocado.
Season with salt and pepper.
Build tacos with steak, onion, reserved cilantro, avocado, and lime wedges.
Serve with salsa alongside.
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