01 - In a mixing bowl, combine olive oil, smoked paprika, cumin, chili powder, garlic powder, onion powder, salt, black pepper, and lime juice. Add chicken thighs or flank steak and turn to coat evenly. Allow to marinate for at least 15 minutes.
02 - Ignite charcoal and allow coals to develop a light gray ash coating. Spread coals evenly and preheat the grill to medium-high heat, approximately 400-450°F.
03 - Place marinated meat directly over the hot coals. Grill chicken thighs for 4 to 5 minutes per side, or flank steak for 2 to 3 minutes per side, until fully cooked with a nicely charred exterior. Transfer to a cutting board and rest for 5 minutes before slicing thinly against the grain.
04 - While the meat rests, place tortillas directly over the grill for 15 to 30 seconds per side until lightly charred, softened, and pliable. Stack and wrap in foil to keep warm.
05 - In a bowl, combine chopped tomatoes, red onion, minced jalapeño, cilantro, and lime juice. Season with salt and pepper to taste. Toss gently and set aside.
06 - Layer sliced grilled meat onto warm tortillas. Top with shredded lettuce, diced tomatoes, red onion, cilantro, and avocado slices. Spoon fresh salsa over each taco and add crumbled queso fresco or shredded cheese if desired. Serve immediately with lime wedges.