In a bowl, gently mix ground meat with garlic, oregano, cumin, paprika, coriander, salt, and pepper until just combined.
In a separate bowl, mix Greek yogurt, cucumber, lemon juice, salt, and dill. Refrigerate until ready.
Heat a large skillet or griddle over medium-high heat and lightly oil the surface.
Place a tortilla on the hot skillet.
Spread a thin layer of seasoned meat onto one side of the tortilla.
Press firmly with a spatula to smash the meat into the tortilla.
Cook meat-side down for 3–4 minutes until deeply browned and crispy.
Flip and cook tortilla-side down for 1–2 minutes until lightly toasted.
Remove from heat and repeat with remaining tortillas.
Rest tacos for 1 minute, then top with tzatziki, onion, tomatoes, and desired toppings.