Grate the cucumber and squeeze out excess moisture. In a mixing bowl, combine cucumber, Greek yogurt, minced garlic, lemon juice, dill, salt, and black pepper. Stir well and refrigerate for at least 30 minutes.

Preheat grill to medium-high heat (about 425°F or 220°C). Lightly oil the grill grates to prevent sticking.

In a bowl, combine ground turkey, diced onion, chopped cilantro, garlic, jalapeño, cumin, paprika, lime juice, cheddar cheese, salt, and pepper. Mix until just combined.

Divide the mixture into six portions and shape into patties about ½ inch thick, pressing a slight indentation in the center.

Place patties on the grill. Cook for 5-6 minutes on one side until charred, then flip and cook for another 5-6 minutes until internal temperature reaches 165°F (74°C).

Remove cooked patties from the grill and let them rest under foil for 3-5 minutes.

Place each patty on a warmed bun. Top with guacamole, sliced cheese, tomato slices, and lettuce.