In a bowl, combine the steak, orange juice, lime juice, ¼ cup chopped cilantro, garlic, salt, paprika, onion powder, black pepper, ground cumin, ground coriander and oregano. Toss everything to coat, cover and refrigerate 1 to 6 hours.
When ready to cook, preheat your grill to 500F (direct heat) or preheat a heavy-bottomed skillet or griddle over medium-high heat. If using a grill, pat the steaks dry, drizzle with some of the avocado oil, and toss to coat. If using a skillet or griddle, pat the steaks dry, add the avocado oil to the pan and heat until shimmering. Transfer the steaks onto the grill (direct heat) or skillet/griddle and cook, undisturbed, until grill marks form or deeply seared, around 4 minutes. Flip and cook the other side until grill marks form or deeply seared and the thickest part of the steak registers 125F for a medium-rare centre, around 4 more minutes. Transfer the steaks to a cutting board and let them rest at least 6 minutes before slicing against the grain into thin strips or small cubes.
While the steaks rest, warm the tortillas on the grill or skillet/griddle for 10-15 seconds per side or until charred. Alternatively, place a heat-safe wire rack over a gas stovetop and warm the tortillas directly over the open flame, 10-15 seconds per side.
In a small bowl, combine the remaining ¼ cup chopped cilantro, finely chopped white onion and small squeeze of lime juice and toss to incorporate.
To assemble the carne asada tacos, spread a layer of guacamole onto the tortilla, top with sliced steak, some of salsa roja and garnish with the fresh cilantro and onion mixture. Serve with extra salsa roja on the side and lime wedges for squeezing.