1. Cut cucumber widthwise into 3 1/2-inch-long sections. Using a vegetable peeler or a mandoline, slice sections lengthwise as thin as possible, yielding flat rectangular slices. Discard any with seeds.

2. Lightly spray a large nonstick skillet with vegetable-oil cooking spray and place over medium-low heat. Add onions and sautee until translucent, 10 to 15 minutes.

3. Add lamb, currants, curry powder, cinnamon, salt, and pepper; raise heat to medium high and cook until meat is browned and cooked through, about 10 to 20 minutes. Remove from heat and stir in chopped mint and yogurt.

4. Form one of the cucumber slices into a cone shape. Fill with 1 to 1 1/2 teaspoons of the meat mixture and garnish with a mint leaf. Repeat procedure, using all the cucumber slices and lamb mixture, and serve immediately.