1. Heat charcoal or gas grill to 400°F.
2. To make Avocado Crema, combine avocado, jalapeño, juice of 1 lime, water, cilantro, yogurt and cumin in food processor or blender; pulse until well blended. Salt to taste.
3. Grill steak for 4 to 6 minutes per side until internal temperature reaches 145°F. Let stand 5 minutes. Slice into very thin strips.
4. Grill sliced onion and chile strips until tender-crisp while grilling steak. Place tortillas on grill for a couple minutes to heat and char slightly. Cut remaining 2 limes into 12 wedges.
5. To assemble tacos, layer grilled onions and poblanos, and carne asada strips onto warm tortillas. Top with pico de gallo, Avocado Crema, and queso fresco. Serve with fresh lime wedge.