Directions

1. Combine lamb, mint, tomato paste, cumin, 1 tsp. salt, and the pepper in a bowl; mix well. Shape lamb mixture into 4 patties of equal size, about 1/3-inch thick. With your thumb, make a shallow indentation about 1 inch wide in the center of each patty. This will help the burgers cook evenly and prevent them from puffing up as they cook.
2. Heat olive oil in a large frying pan over medium heat. When it’s hot, add lamb patties and cook, turning once, until nicely browned and cooked to medium (160°F in thickest part when tested with an instant-read thermometer), 12-14 minutes.
3. Meanwhile, combine yogurt, feta cheese, garlic, and 1/8 tsp. salt in a bowl, mashing with a fork until the mixture is fairly smooth. (Sauce can be made up to 2 days ahead and chilled.)
4. Set the bottom half of each hamburger bun on a serving plate and top with a lettuce leaf, tomato slice, 4 cucumber slices, and a lamb burger. Spoon on feta sauce, then set the tops of the hamburger buns in place.