Greek Meatballs and Tzatziki

Name: Greek Meatballs and Tzatziki
Ingredients: 2 slices white bread, 1-inch thick; 1/4 to 1/2 cup milk, to moisten; 1/2 seedless cucumber; Kosher salt; 3 tablespoons EVOO; 1 1/2 pounds ground lamb or beef; Freshly ground pepper; 1/4 cup finely chopped fresh mint; 3 tablespoons grated red onion; 1 tablespoon finely chopped fresh oregano; 2 pinches cinnamon; 3 cloves garlic, grated or pasted; 1 large egg; Zest and juice of 1 lemon; 4 pocket-less pitas or flat breads, cut into wedges; 1 1/2 cups Greek yogurt; 1/4 cup fresh dill; 1 teaspoon ground cumin