Lamb Burgers with Tzatziki Sauce and Parsley Salad

Name: Lamb Burgers with Tzatziki Sauce and Parsley Salad
Ingredients: 2 pounds ground lamb; 1 ½ teaspoons salt; ¼ teaspoon ground black pepper; 2 teaspoons Madras curry powder; 2 cups Greek yogurt; 1 English cucumber, peeled, seeded, and chopped; ¼ cup chopped fresh mint; 1 teaspoon lemon zest; 1 tablespoon fresh lemon juice; 2 medium vine-ripened tomatoes, chopped; 1 cup packed parsley leaves; ½ medium red onion, thinly sliced; 2 tablespoons extra-virgin olive oil; 8 individual pitas or 4 regular pitas