In a large bowl combine all of the ingredients for the meatballs. Using clean hands, mix until well combined. Form into 1 inch balls, and place on a baking sheet. Bake for 15-20 minutes, until cooked thru.
Meanwhile, prepare the tzatziki sauce. Grate the cucumber, including the peel. Wrap in a clean kitchen towel, and squeeze to remove the liquid. In a small bowl combine yogurt, drained cucumber, lemon juice, dill, garlic, salt and pepper. Store in the fridge until ready to serve.
To serve top each pita with a couple meatballs, tzatziki sauce and a few tomatoes.