Place a large non-stick skillet over medium-high heat. Add the ground beef and cook, breaking it up with a spatula, until browned and cooked through.
Drain any excess fat from the skillet. Reduce heat to medium-low and stir in the chili powder, cumin, garlic powder, onion powder, sea salt, and black pepper.
Add a splash of water, about one to two tablespoons, to the skillet to help the spices coat the beef evenly. Simmer for 2-3 minutes until the liquid has evaporated.
While the beef simmers, finely shred the romaine lettuce, dice the tomato, and mince the red onion.
Warm the corn tortillas in a dry skillet over medium heat for 30 seconds per side until pliable and slightly toasted.
Assemble the tacos by dividing the seasoned beef between the two tortillas.
Top each taco with shredded lettuce, diced tomatoes, minced red onion, a dollop of Greek yogurt, and fresh cilantro.
Squeeze fresh lime juice over the tacos just before serving for a bright, citrusy finish.