Ingredients

TZATZIKI

½ cup coarsely grated unpeeled English cucumber
¾ cup plain Greek yogurt
2 teaspoons extra-virgin olive oil
2 teaspoons fresh lemon juice
1 clove garlic, minced
Kosher salt
Coarsely ground black pepper

1-½ pounds ground lamb
2 tablespoons minced fresh mint leaves
1 clove garlic, minced
1 large, ripe beefsteak tomato, cut crosswise into thick slices
4 hamburger buns, split
4 leaves red or green lettuce

Directions

Place the grated cucumber in a fine-mesh strainer and press firmly to squeeze out the excess liquid, or wrap the grated cucumber in paper towels and squeeze out the excess liquid. Discard the liquid. Transfer the cucumber to a small bowl. Add the remaining tzatziki ingredients, including ¼ teaspoon salt and ⅛ teaspoon pepper, and stir to combine. Cover and keep refrigerated until ready to use, up to 8 hours.

Combine the ground lamb, mint, garlic, 1 teaspoon salt, and ½ teaspoon pepper, and then gently form four patties of equal size, each about ¾ inch thick. With your thumb or the back of a spoon, make a shallow indentation about 1 inch wide in the center of the patties to keep them from forming a dome as they cook. Refrigerate until ready to grill.

Prepare the grill for direct cooking over medium heat (350° to 450°F).

Grill the patties over direct medium heat, with the lid closed, until cooked to well done (160°F), 7 to 9 minutes, turning once. During the last 30 seconds to 1 minute of grilling time, toast the buns, cut side down, over medium heat.
Season the tomato slices evenly with ¼ teaspoon salt. Build each burger on a bun with a lettuce leaf, a tomato slice, a patty, and tzatziki. Serve warm.